79 Guide Chapter 2

In 1978, the National Opinion Research Center (NORC) at the University of Chicago created a list of housing units in selected areas of the United States for the first NLSY79 interview. NORC interviewers went to a random sample of these homes and performed a short interview, called the screener, which provided basic information on every resident of the household. NORC also extracted a random sample of Department of Defense records to ensure the survey included members of the military.

Together these two processes provided information, such as name, age, sex, race, and address, on more than 155,000 people. This information was used to identify all individuals ages 14 to 21 as of December 31, 1978. Based on this screener information, each appropriately aged individual was assigned to one of the sample groups. Then, in 1979, NORC interviewers asked individuals on this list to participate in the first NLSY79 interview. Any person who completed the first round interview is considered a member of the NLSY79 cohort.

Three independent probability samples compose the NLSY79. These samples are designed to represent the entire population of youth aged 14 to 21 as of December 31, 1978, residing in the United States on January 1, 1979. The three samples are:

(1) a cross-sectional sample (6,111) designed to represent the noninstitutionalized civilian segment of young people living in the United States in 1979 and born January 1, 1957, through December 31, 1964

(2) a set of supplemental samples (5,295) designed to oversample civilian Hispanic or Latino, black, and economically disadvantaged, nonblack/non-Hispanic youths born in the same time period

(3) a military sample (1,280) designed to represent the population born January 1, 1957, through December 31, 1961, serving in the military as of September 30, 1978. The inclusion of the military sample allows comparative civilian-military analyses.

Beginning in 1986, additional information was collected about children born to female NLSY79 respondents. The child sample, when weighted, is representative of American children born to the population of women born in 1957 through 1964 and living in the United States in 1979. The sampling procedures used by NORC to select the civilian and military subsamples differed and are discussed separately below. For additional information on NLSY79 sampling procedures, see Frankel et al. (1983) and the Interviewer’s Manual for the 1978 household screening (NORC 1978). Sampling issues related to the Children of the NLSY79 are discussed in Baker et al. (1993) and in the NLSY79 Child & Young Adult Data Users Guide.

2.2 Screening

To find people of the correct age and ethnic composition, NORC screened a large number of individuals in two separate procedures. First, household screening interviews were conducted to select the NLSY79 civilian cross-sectional and supplemental subsamples from the civilian population. Then, a second screening was done to identify the military sample. While the civilian screening made use of field interviewers going to selected households, the military sample was drawn from Department of Defense records.

NORC administered the civilian sample screening interview in approximately 75,000 dwellings and group quarters. These interviews occurred in 1,818 sample segments of 202 Primary Sampling Units (PSUs), which included most of the 50 States and the District of Columbia. The screening interview was designed to elicit information that would identify persons eligible for inclusion in the NLSY79 sample. The civilian screening interviews were completed within 91.2 percent of the cross-sectional and 91.9 percent of the supplemental occupied dwelling units selected for screening.

Cross-Sectional Sample: Approximately 18,000 of the screening interviews were carried out among 918 sample segments in 102 Primary Sampling Units (PSUs), which were selected from the NORC Master Probability Sample of the United States.

Supplemental Sample: A total of 57,000 screening interviews for the supplemental sample were carried out among 900 sample segments in a 100-PSU sample specifically designed to produce statistically efficient samples of Hispanics or Latinos, blacks, and economically disadvantaged, nonblack/non-Hispanics. The NLS sample design, which selected every eligible person connected to the household, generated a representative sample of siblings and spouses living in the same household and satisfying the age restrictions stated above. However, NLSY79 samples do not contain nationally representative samples of siblings and spouses of all ages and living arrangements. When the NLSY79 is used to study sibling pairs and married couples, care must be used in generalizing from the findings of such studies.

Procedures were also developed to establish “linkages” between dwellings and certain types of individuals who might be temporarily absent. As part of the initial screening for the civilian sample, household respondents were asked if there were any persons with primary family connections to the household who were away from the household at the time. Included in this group were college students, military personnel, and those in prisons or other institutions. Household screener respondents were also asked to name persons who might occasionally stay at the dwelling who did not have any other “usual place of residence.” For each individual identified in this process, an attempt was made to determine whether the individual would be “linked” to some other household, such as college students living off campus in their own dwelling units. All individuals without other linkages were included in the household composition for purposes of sampling.

Military Sample: Persons on active military duty as of September 30, 1978, were sampled from rosters provided by the Department of Defense. No formal screening interview was conducted.

2.3 Sampling Process

Civilian Samples: All civilian sample selection was accomplished through a multi-stage stratified area probability sample of dwelling units and group quarter units. A moderate degree of oversampling of dwelling units within sample listing segments was employed in order to increase the sample composition with respect to the targeted groups of the supplemental sample.

Base year samples of Hispanics or Latinos, blacks, and economically disadvantaged, nonblack/non-Hispanics were selected from individuals identified in both the 102 PSU cross-sectional sample and the 100 PSU special purpose sample. To the extent that individuals identified in the screening phase were obtained with different probabilities of selection (because of selective oversampling), the weighting of base year samples attempts to minimize these probability differences. Since the use of oversampling tends to decrease sample efficiency (that is, variance), attempts were made to minimize required oversampling.

Figure 2.3.1 Number of Respondents Born Each Month by Birth Year ¹

¹ The month and year of birth is taken from the 1978 screener (R00003. and R00005.). Respondents were asked about their dates of birth again in 1981, but the use of these values does not change the results indicated above. The 1957–63 value can be found by averaging the total number of birth dates reported for each month over all of the years.

Assignment of a youth to either the cross-sectional or supplemental sample was made using information collected during the household screening interviews and a set of coding instructions prepared by NORC. During the 1978 household screening interviews—from which the sample of NLSY79 respondents was drawn—information was collected on the sex, race, and ethnic origin of each household member and on the total income of the family unit during the past 12 months. A detailed set of coding procedures transformed these raw data into a combined racial/ethnic identifier and an economically disadvantaged qualifier. These criteria were used not only to assign a youth to one of the various subsamples, but also to specify the primary race or ethnicity variable, which provides the basis for weighting.

Other technical information on the sample assignment process can be found in (1) the Household Screener and Interviewer’s Manual (NORC 1978), which includes a copy of the screening instrument and detailed instructions to interviewers for administering the race, ethnic origin, and family income questions; (2) the Technical Sampling Report (Frankel et al. 1983), which describes the NLSY79 sample selection procedures for the civilian and military subsamples; (3) the 10/4/78 NORC memorandum, which provides the rules used to assign race and poverty status from responses to the screening questions; (4) a copy of the 1978 poverty income levels by family size and farm-nonfarm residence; and (5) the “Race, Ethnicity, & Nationality” section of this User’s Guide, which summarizes information in these documents as it relates to the assignment of “Hispanic,” “Black,” and “non-Hispanic, nonblack” origins used in the sample identification code variable (R01736.) and the race/ethnicity variable (R02147.). Base year interviews with the three subsamples were conducted between January and mid-August 1979. Table 2.3.1 summarizes base year completion rates for each subsample.

Table 2.3.1 Base Year Interview Completion: NLSY79

Cross-Sectional Sample: Following the initial screening process, 6,812 individuals from the cross-sectional sample were designated to be interviewed in the base year; of those, 90 percent or 6,111 respondents were actually interviewed in 1979. The cross-sectional sample is designed to maximize the statistical efficiency of samples which are “cross-sectional” with respect to the rural population. Specifically, through the several stages of sample selection (counties, enumeration districts-block groups, sample listing units), probabilities of selection are based upon either total population or total housing units. Except for the economically disadvantaged supplemental sample, sampling of nonblack/non-Hispanic respondents was restricted to the 102 PSU National Sample.

Supplemental Sample: After screening, 5,969 individuals from the supplemental sample were designated for base year interviews, and of these, 89 percent or 5,295 respondents were actually interviewed. Stratification specifically relevant for Hispanics or Latinos, non-Hispanic blacks, and economically disadvantaged, nonblack/non-Hispanics was used. Probability proportional to size procedures were based on size measures for these groups rather than for the general population, making it possible to more nearly equalize the distribution of the targeted groups among the various sampling units than would otherwise be the case.

Military Sample: Of the 1,793 military youth selected for interviews, 1,280 or 72 percent were interviewed in 1979. Selection of the military sample was accomplished in two stages. In the first stage, a sample of approximately 200 “military units” was selected. These units were selected with probabilities proportional to the number of persons born in 1957 through 1961 and serving in the military unit as of September 30, 1978.

Within selected units, persons born in 1957 through 1961 were sampled with probabilities inversely proportional to the first-stage selection probability. Females were sampled at a rate approximately six times that of males in order to produce approximately 850 males and 450 females. Within each sex, the sample was stratified on the basis of branch of military service (Army, Navy, Air Force, and Marine Corps) and geographic location (Eastern U.S., Western U.S., Europe, Far East, other). Of those interviewed in 1979, 824 military respondents were male and 456 were female (see Table 2.3.2). The entire military sample was eligible for interview from 1979–84.

Table 2.3.2 NLSY79 Military Respondents Interviewed in 1979 by Sex, Race & Military Branch

Child Sample: The number of children assessed during a given child survey year is a function of the number of children born to interviewed NLSY79 mothers, the number of children living in the homes of those mothers, and, finally, the number of those children actually interviewed. Of the 5,842 NLSY79 females eligible for the first child interview in 1986, more than 2,900 mothers and 4,971 children were interviewed. From this sample of eligible children, assessment data were collected for 4,786. Table 1.5.1 in Chapter 1 presents sample sizes across subsequent survey years.

2.4 Interview Schedule & Fielding Periods

The original interview schedule, which called for yearly personal interviews with NLSY79 respondents, was retained from 1979 through 1986. In 1987, budget constraints dictated a limited phone interview rather than a personal interview. Personal interviews resumed with the 1988 round and continued yearly until 1994. NLSY79 respondents have been interviewed in even-numbered years since 1994.

The initial NLSY79 interviews were conducted between late January and mid-August 1979. The next several interviews were fielded in the first six months of the year; subsequent surveys have typically begun in late spring and ended in the fall or early winter. Table 2.4.1 provides information on the fielding periods for NLSY79 respondents.

Table 2.4.1 NLSY79 Fielding Periods

From 1979 until 1986, timing of the fielding period was designed to allow all respondents still in school to be interviewed before they left to take temporary summer jobs. Detailed information was collected for jobs held by respondents while they were in school. Since the youngest respondents in the survey were 23 years old in 1988, the shift in fielding periods after 1987 had a relatively small impact on information on jobs held while in school. An attempt was made during the initial survey years to keep the fielding period for an individual respondent approximately the same from year to year in order to assure that the time between interviews was approximately twelve months.

Researchers conducting analyses on topics where time periods are critical should carefully examine the reference period of the questions, the actual interview date, and the duration since the preceding interview.

2.5 Interview Methods & Target Universe

During each survey round, NORC attempts to reach all youth within the active samples. No respondents have been routinely excluded from locating efforts with the exception of respondents who have died or, in a small number of cases, were judged to be extremely difficult. The permanent NLSY79 sample designated for interviewing during the 1979–84 interview years consisted of all civilian and military youth who were interviewed in the base year and who were alive at the survey date.

In 1985, when interviewing of the full military sample ceased, the total NLSY79 sample size dropped from 12,686 to 11,607. Retained for interviewing in post-1984 surveys were 201 military respondents randomly selected from the entire military sample of 1,280; the remaining 1,079 military respondents were eliminated from the sample. The 201 military members who were retained included (1) 51 cases that would have been selected as part of a random sample of youth including the military and (2) 150 additional cases selected to provide a sufficient number of original military sample members to avoid overly large sampling variability for the military sample. Beginning in 1991, the 1,643 members of the economically disadvantaged, nonblack/non-Hispanic supplemental sample were no longer interviewed. Unless otherwise noted, eligible sample sizes reported in NLS publications include deceased and difficult-to-field respondents but exclude those respondents dropped from the sample. Additional information on numbers and characteristics of noninterviewed respondents can be found in the "Reasons for Noninterview" section later in this chapter.

NLSY79 respondents reside in each of the 50 States and the District of Columbia, U.S. territories, and countries abroad. Locating respondents is a coordinated effort of NORC’s central office, its locating shop, and local-level field staff. Prior to fielding, NORC’s central office sends a short, informative “advance letter” to each respondent reminding him or her of the upcoming interview and confirming the respondent’s current address and phone number. Field staff locating efforts begin with this information and locator sheets.

At the local level, interviewers are responsible for contacting all respondents in their caseloads and for tapping additional local resources (post offices, departments of motor vehicles and vital statistics, and so forth) to locate those respondents who have moved. If an interviewer is unsuccessful in locating a respondent, the case is transferred to the field manager who undertakes additional locating strategies.

In the event that such local-level efforts fail, the case is forwarded to NORC’s locating shop in Chicago where the complete files on each respondent can be accessed and used for additional locating efforts. Respondents who cannot be located are only a small percentage of the total not interviewed in a given survey year. (For more information about noninterviews, refer to section 2.6 in this chapter.)

In addition to its comprehensive locating efforts, NORC makes every effort to convert initial respondent refusals to completed interviews. For uncooperative respondents, NORC sends “refusal conversion letters” designed to encourage continued participation in the survey. Over the years, NORC has successfully conducted interviews with 33–50 percent of respondents who initially refused. NORC’s extensive locating methods and its conversion strategy, combined with its close monitoring of response rates for each of the subsamples of the NLSY79, have resulted in relatively high retention rates for a longitudinal panel of this duration.

While personal interviewing has been the primary contact method used for all but one round of the NLSY79, it is not the exclusive method. In previous rounds telephone contact to complete the survey occurred under certain circumstances, such as when the respondent resided in a remote area or field staff determined that phone contact was the preferred method of interviewing a respondent. The number of telephone interviews has increased in recent years as respondents have become more dispersed or expressed a preference for phone interviews. The percent of surveys conducted by telephone for each survey year are shown in Table 2.5.1.

Table 2.5.1 Percent of NLSY79 Interviews Conducted by Telephone, 1979-2006

In rare cases, interviews are conducted in whole or in part with a proxy, a person other than the respondent (for example, four in 1991, two in 1992). A variable, entitled ‘Interview Conducted with Proxy Respondent,’ is present in the data to identify these interviews. In order to conduct such an interview, individual approval must be obtained by the NORC central office and the circumstances documented.

A Spanish version of all survey instruments, except the Young Adult questionnaire, is prepared and NORC employs bilingual, Spanish-speaking interviewers. During the 1992 interview, for example, 104 respondents requested the use of a Spanish version of the questionnaire.

The average length of a personal interview is approximately one hour. The 1987 telephone interviews were completed within about 40 minutes, while the administration of the child assessments added approximately 45 minutes to the total survey administration time for each child.

Until 1989, the NLSY79 was conducted using only and pencil interviews (PAPI)” paper-and-pencil interviews (PAPI). PAPI interviews were performed by interviewers filling in the relevant fields of large printed questionnaire booklets. While these booklets were inexpensive to produce, interviewers could make mistakes in following complicated skip patterns and filling in answers. Moreover, after all interviews were completed, additional office staff were needed to transcribe the information collected. Computer-assisted personal interviews (CAPI) were designed to eliminate many of these problems. For assisted personal interviews (CAPI)” CAPI interviews, interviewers take laptop computers into the field instead of questionnaire booklets. A computer program automatically selects the next question, prevents interviewers from entering illegal values, and warns interviewers about questionable answers. The computer also eliminates the need for data transcription except for specific items collected verbally and coded later.

While the majority of interviews in 1990 were collected using PAPI materials, a subset of one fourth of respondents was administered their survey using CAPI methods in order to test the viability and reliability of CAPI administration. Due to the success of these experiments, the NLSY79 interviews became fully CAPI administered beginning in 1993. Users interested in the results of these experiments should consult Olsen (1991).

From 1979 until 1994, each respondent was paid $10 upon completion of the interview. Respondents were paid $20 beginning with the 1996 interview and $40 beginning with the 2002 interview. NLSY79 mothers participating in the child assessments receive an additional $10 per child. Through 1994, young adults were paid $10. Beginning with the 1996 interview they received $20 and in 2004 received $40. NLSY79 respondents who participated in the 1980 ASVAB testing were paid $50 each.

Retention vs. Response Rates

Retention rates for NLSY79 respondents throughout the first 16 rounds of the survey exceeded or were very near 90 percent. Rounds 17 and 18 saw retention rates of approximately 85 percent. Retention rate is calculated by dividing the number of respondents interviewed by the number of respondents remaining eligible for interview. All 1979 (round 1) respondents including those reported as deceased are eligible for interviews, with the exception of those who have been permanently dropped from the sample. In the round 22 (2006) survey, 7,654 civilian and military respondents out of the 9,964 eligible were interviewed, for an overall retention rate of 76.8 percent. Retention rates for each survey are shown in Table 2.5.2. This table also shows which interviews were conducted with paper-and-pencil interviewing (PAPI) and which were executed with computer-assisted personal interviewing (CAPI).

The number of respondents can also be expressed as a percentage of the number of base year respondents not known to be deceased. This is referred to as the response rate and is reported in Table 2.5.3 for each survey round. As of 2006, 456 main respondents (4.6 percent of the respondents eligible for interview) had been reported as deceased. The response rate for those believed to be alive is 80.5 percent.

Table 2.5.2 Sample Sizes & Retention Rates by Sample Type: NLSY79

		Cross-Sectional Sample		Supplemental Sample		Military Sample		Total Sample
Year	Type & Mode of Interview	Total	Retention Rate ¹	Total	Retention Rate ¹	Total	Retention Rate ¹	Total	Retention Rate ¹
1979	Personal/PAPI	6111	-	5295	-	1280	-	12686	-
1980	Personal/PAPI	5873	96.1	5075	95.9	1193	93.2	12141	95.7
1981	Personal/PAPI	5892	96.4	5108	96.5	1195	93.4	12195	96.1
1982	Personal/PAPI	5876	96.2	5036	95.1	1211	94.6	12123	95.6
1983	Personal/PAPI	5902	96.6	5093	96.2	1226	95.8	12221	96.3
1984	Personal/PAPI	5814	95.1	5040	95.2	1215	94.9	12069	95.1
1985	Personal/PAPI	5751	94.1	4957	93.6	186²	92.5	10894³	93.9
1986	Personal/PAPI	5633	92.2	4839	91.4	183	91.1	10655	91.8
1987	Telephone/PAPI	5538	90.6	4768	90.1	179	89.1	10485	90.3
1988	Personal/PAPI	5513	90.2	4777	90.2	175	87.1	10465	90.2
1989	Personal/PAPI/CAPI	5571	91.2	4853	91.7	181	90.0	10605	91.4
1990	Personal/PAPI/CAPI	5498	90.0	4755	89.8	183	91.0	10436	89.9
1991	Personal/PAPI	5556	90.9	3281⁴	89.9	181	90.0	9018⁵	90.5
1992	Personal/PAPI	5553	90.9	3280	89.8	183	91.0	9016	90.5
1993	Personal/CAPI	5537	90.6	3293	90.2	181	90.0	9011	90.4
1994	Personal/CAPI	5457	89.3	3256	89.2	178	88.6	8891	89.2
1996	Personal/CAPI	5290	86.6	3171	86.8	175	87.1	8636	86.7
1998	Personal/CAPI	5159	84.4	3065	83.9	175	87.1	8399	84.3
2000	Personal/CAPI	4949	81.0	2921	80.0	163	81.1	8033	80.6
2002	Personal/CAPI	4775	78.1	2792	76.5	157	78.1	7724	77.5
2004	Personal/CAPI	4686	76.7	2818	77.2	157	78.1	7661	76.9
2006	Personal/CAPI	4630	75.8	2862	78.4	162	80.6	7654	76.8

¹ Retention rate is defined as the percentage of base year respondents within each sample type remaining eligible who were interviewed in a given survey year. Included in the eligible sample are deceased and difficult to field respondents whom NORC does not attempt to contact.
² A total of 201 military respondents were retained from the original sample of 1,280.
³ The total number of civilian and military respondents in the NLSY79 at the beginning of the 1985 survey was 11,607.
⁴ Economically disadvantaged, nonblack/non-Hispanic female and male members of the supplemental subsample are not eligible for interview as of the 1991 survey year. Remaining eligible for interview in post-1990 surveys are 3,652 black and Hispanic or Latino respondents of the supplemental sample, of whom 3,281 were interviewed in 1991.
⁵ The total number of civilian and military respondents in the NLSY79 at the beginning of the 1991 survey was 9,964.

Table 2.5.3 Response Rates (Excluding Deceased Sample Members) by Sample Type: NLSY79
NOTE: This table was revised on 3/20/07.

2.6 Reasons for Noninterview

A ‘Reason for Noninterview’ variable is constructed for each survey year (excluding 1979) in the NLSY79 and provides an explanation of why an interview could not be conducted or completed with a respondent. The cause of noninterview is assigned by the NORC interviewer to each respondent designated as a member of the eligible sample for a given survey year. Typical coding categories have included reasons such as an interview being refused by the respondent or by the respondent’s parent, the respondent or family unit not being located, or the respondent being reported as deceased.

Beginning in the 1980s, two administrative categories were added. One reflected a decision by NORC not to attempt to interview certain sample members who were determined to be extremely difficult to interview. The second category indicates that, due to funding cutbacks, interviews would not be attempted with certain members of one or more of the NLSY79 subsamples. Thus, beginning in 1985, interviews ceased for 1,079 respondent members of the military subsample; each was permanently assigned a reason for noninterview of “military sample dropped.” A second group of respondents, those belonging to the supplemental economically disadvantaged, nonblack/non-Hispanic sample, was similarly dropped from interviewing beginning with the 1991 survey. The target universe for each survey year—that is, the respondents whom NORC attempts to interview—thus includes all respondents interviewed in the initial survey year exclusive of those who were (1) reported deceased at an earlier interview; (2) dropped from the sample; or (3) judged to be extremely difficult to interview.

The tables below present the number of respondents not interviewed across survey years by reason, sex, race or ethnicity, and sample type.

Table 2.6.1 Reasons for Noninterview: NLSY79 1979-2006

Survey Year	Total Interviewed	Total Not Interviewed	Reason for Noninterview
Survey Year	Total Interviewed	Total Not Interviewed	Refusal	Can't Locate	Deceased	Other	Difficult Cases	Dropped¹
1979	12686	0	0	0	0	0	0	0
1980	12141	545	253	217	9	66	0	0
1981	12195	491	220	114	29	128	0	0
1982	12123	563	177	209	44	50	83	0
1983	12221	465	220	124	57	37	27	0
1984	12069	617	374	151	67²	25	0	0
1985	10894	1792	331	152	79	26	125	1079
1986	10655	2031	524	200	95	36	97	1079
1987	10485	2201	508	293	110	68	143	1079
1988	10465	2221	587	248	127	83	97	1079
1989	10605	2081	525	188	141	46	102	1079
1990	10436	2250	662	246	152	52	59	1079
1991	9018	3668	507	202	144²	23	71	2722
1992	9016	3670	526	158	156	29	80	2722
1993	9011	3675	541	122	177	24	91	2722
1994	8891	3795	604	146	204	26	95	2722
1996	8636	4050	708	184	243	48	147	2722
1998	8399	4287	731	272	275	136	153	2722
2000	8033	4653	1037	353	313	123	105	2722
2002	7724	4962	1092	410	346	135	257	2722
2004	7661	5025	1134	452	399	202	116	2722
2006	7654	5032	1392	313	456	56	93	2722

¹Two groups of NLSY79 respondents have been dropped from interviewing: (1) 1,079 members of the 1,280 military subsample were dropped after the 1984 survey and (2) the 1,643 members of the supplemental economically disadvantaged, nonblack/non-Hispanic subsample were dropped after the 1990 interview.
² Twenty-two respondents of the 1,643 supplemental economically disadvantaged, nonblack/non-Hispanic sample members dropped after 1990 had been reported as deceased prior to 1991 and two members of the military were reported as deceased prior to 1984. All twenty-four remain classified as dead in the RNI variable. To construct the above table, however, these individuals were reclassified from deceased to dropped. In particular military respondent 10657 and respondent 10802 were reclassified from deceased to dropped. Among the supplemental economically disadvantaged, nonblack/non-Hispanic subsample the 22 reclassified members were identified by have a reason for noninterview code of 65 in sample years greater than 1990 and a sample id code of 9 or 12.

Table 2.6.2 Reasons for Noninterview by Sex: NLSY79 1980-2006

Survey Year	Total Not Interviewed		Reason for Noninterview
	Total Not Interviewed		Refusal		Can't Locate		Deceased		Other		Difficult Case		Dropped¹
	M	F	M	F	M	F	M	F	M	F	M	F	M	F
1980	311	234	134	119	129	88	4	5	44	22	0	0	0	0
1981	272	219	109	111	61	53	18	11	84	44	0	0	0	0
1982	315	248	103	74	116	93	30	14	35	15	31	52	0	0
1983	255	210	110	110	71	53	36	21	26	11	12	15	0	0
1984	348	269	186	188	96	55	44	23	22	3	0	0	0	0
1985	1032	760	172	159	93	59	52	27	20	6	57	68	638	441
1986	1166	865	271	253	122	78	65	30	26	10	44	53	638	441
1987	1287	914	273	235	186	107	77	33	43	25	70	73	638	441
1988	1250	971	296	291	138	110	89	38	43	40	46	51	638	441
1989	1207	874	268	257	123	65	96	45	31	15	51	51	638	441
1990	1291	959	322	340	160	86	103	49	34	18	34	25	638	441
1991	1932	1736	264	243	136	66	103	41	16	6	33	38	1380	1342
1992	1922	1748	266	260	106	52	111	45	19	9	40	40	1380	1342
1993	1939	1736	275	265	86	36	130	47	19	4	49	42	1380	1342
1994	1992	1803	309	294	99	47	146	58	13	12	45	50	1380	1342
1996	2128	1922	352	356	124	60	175	68	27	19	70	77	1380	1342
1998	2303	1984	377	354	189	83	197	78	84	50	76	77	1380	1342
2000	2483	2170	513	524	238	115	219	94	75	48	58	47	1380	1342
2002	2634	2328	527	565	275	135	240	106	81	54	131	126	1380	1342
2004	2726	2299	554	580	299	153	270	129	122	80	101	15	1380	1342
2006	2665	2367	675	717	207	106	305	151	32	24	66	27	1380	1342

¹Two groups of NLSY79 respondents have been dropped from interviewing: (1) 1,079 members of the 1,280 military subsample were dropped after the 1984 survey and (2) the 1,643 members of the supplemental economically disadvantaged, non-black/non-Hispanic subsample were dropped after the 1990 interview. Of the 1,643 supplemental economically disadvantaged, non-black/non-Hispanic subsample members dropped, 22 here are reclassified as members of the supplemental sample.

Table 2.6.3 Reasons for Noninterview by Race/Ethnicity: NLSY79 1980-2006

Table 2.6.4 Reasons for Noninterview by Sample Type: NLSY79 1980-2006

2.7 Sample Representativeness & Attrition

This section reviews the number of respondents by race, sex, and NLSY79 sample type who have continued to be interviewed during all surveys. It also takes a brief look at the racial composition of the cohort at the initial and latest survey points. Table 2.7.1 shows the number of respondents, excluding dropped respondents, who were interviewed at all survey points. This table exhibits the high degree of NLSY79 retention. From 1979 to 2004 the survey has been administered 22 times; excluding dropped individuals, the average respondent has completed 19. 7 interviews.

Table 2.7.1 Percentage of NLSY79 Respondents, Excluding Dropped Respondents, Who Answered Every Survey: 1979-2006

Table 2.7.2 Cohort Characteristics by Race: 1979-2006

Tables 2.7.3–2.7.5 show the distribution of the number of interviews completed by respondents, broken down by sex, race, and sample type. The “# who completed” column shows how many respondents completed exactly that number of surveys. These numbers refer to any surveys completed since the NLSY79 began, not necessarily consecutive surveys completed or surveys completed in particular years. The cumulative percent column shows a cumulative total percent of those completing at least a given number of surveys rather than a percentage of those completing an exact number of surveys. Readers should note the attrition suggested in Table 2.7.3 greatly overstates the amount of lost information. The NLSY79 asks detailed questions about work history, education, training, marital status, and fertility since the date of the respondent’s last interview. These retrospective questions capture information lost due to missed interviews. Hence, a perfect response record is not needed for researchers to understand how the respondent’s life changes over time, unless he or she leaves the survey forever.

Table 2.7.3 Number of Interviews Respondents Completed out of 22 Surveys by Sex: NLSY79 1979-2006

Total			Males			Females
# of Surveys¹	# who Completed	Cumulative Percent	# of Surveys¹	# who Completed	Cumulative Percent	# of Surveys¹	# who Completed	Cumulative Percent
22	5538	55.6	22	2517	50.1	22	3021	61.1
21	5736	57.6	21	2615	52.1	21	3121	63.2
20	1233	12.4	20	679	13.5	20	554	11.2
19	660	12.3	19	380	7.6	19	280	5.7
18	491	6.6	18	288	5.7	18	203	4.1
17	324	4.9	17	192	3.8	17	132	2.7
16	249	3.3	16	142	2.8	16	107	2.2
15	201	2.0	15	122	2.4	15	79	1.6
14	139	1.4	14	83	1.7	14	56	1.1
13	128	1.3	13	69	1.4	13	59	1.2
12	103	1.0	12	64	1.3	12	39	0.8
11	88	0.9	11	44	0.9	11	44	0.9
10	79	0.8	10	36	0.7	10	43	0.9
9	85	0.9	9	43	0.9	9	42	0.9
8	77	0.8	8	45	0.9	8	32	0.7
7	85	0.9	7	53	1.1	7	32	0.7
6	71	0.7	6	45	0.9	6	26	0.5
5	59	0.6	5	36	0.7	5	23	0.5
4	45	0.5	4	23	0.5	4	22	0.5
3	30	0.3	3	19	0.4	3	11	0.2
2	40	0.4	2	27	0.5	2	13	0.3
1	41	0.4	1	18	0.4	1	23	0.5
Total	9964	100	Total	5023	100	Total	4941	100

Note: Universe excludes the 1,079 members of the military subsample and the 1,643 members of the economically disadvantaged, non-black/non-Hispanic subsample dropped from interviewing; it includes the remaining 9,964 eligible members.
¹ Surveys completed in any year, not necessarily consecutive survey years.

Table 2.7.4 Number of Interviews Respondents Completed out of 22 Surveys by Race: NLSY79 1979-2006

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Total Sample			Hispanic or Latino			Black			Non-Black/Non-Hispanic
# of Surveys¹	# who Completed	Cumul. Percent	# of Surveys¹	# who Completed	Cumul. Percent	# of Surveys¹	# who Completed	Cumul. Percent	# of Surveys¹	# who Completed	Cumul. Percent
22	5,538	55.6	22	916	46.7	22	1,647	54.9	22	2,975	59.5
21	1,200	12	21	291	14.8	21	413	13.8	21	496	9.9
20	661	6.6	20	180	9.2	20	206	6.9	20	275	5.5
19	474	4.8	19	110	5.6	19	161	5.4	19	203	4.1
18	389	3.9	18	91	4.6	18	108	3.6	18	190	3.8
17	256	2.6	17	47	2.4	17	75	2.5	17	134	2.7
16	251	2.5	16	61	3.1	16	70	2.3	16	120	2.4
15	161	1.6	15	37	1.9	15	45	1.5	15	79	1.6
14	137	1.4	14	35	1.8	14	29	1.0	14	73	1.5
13	115	1.2	13	19	1.0	13	35	1.2	13	61	1.2
12	94	0.9	12	17	0.9	12	28	0.9	12	49	1.0
11	85	0.9	11	26	1.3	11	26	0.9	11	33	0.7
10	78	0.8	10	13	0.7	10	29	1.0	10	36	0.7
9	85	0.8	9	16	0.8	9	27	0.9	9	42	0.8
8	75	0.8	8	26	1.3	8	14	0.5	8	35	0.7
7	82	0.8	7	15	0.8	7	15	0.5	7	52	1.0
6	73	0.7	6	16	0.8	6	19	0.6	6	38	0.8
5	58	0.6	5	9	0.5	5	14	0.5	5	35	0.7
4	42	0.4	4	11	0.6	4	13	0.4	4	18	0.4
3	30	0.3	3	7	0.4	3	6	0.2	3	17	0.3
2	39	0.4	2	7	0.4	2	12	0.4	2	20	0.4
1	41	0.4	1	11	0.6	1	9	0.3	1	21	0.4
Total	9964	100	Total	1961	100	Total	3001	100	Total	5002	100

Note: Universe excludes the 1,079 members of the military subsample and the 1,643 members of the economically disadvantaged, nonblack/non-Hispanic subsample dropped from interviewing; it includes the remaining 9,964 eligible members.
¹ Surveys completed in any year, not necessarily consecutive survey years.

Table 2.7.5 Number of Interviews Respondents Completed out of 22 Surveys by Sample Type: NLSY79 1979-2006

2.8 Sample Weights

In each survey year a set of sampling weights is constructed. These weights provide the researcher with an estimate of how many individuals in the United States each respondent’s answers represent. Weighting decisions for the NLSY79 are guided by the following principles: (1) individual case weights are assigned for each year in such a way as to produce group population estimates when used in tabulations, and (2) the assignment of individual respondent weights involves at least three types of adjustment, with additional considerations necessary for weighting of NLSY79 Child data.

The interested user should consult the NLSY79 Technical Sampling Report (Frankel, Williams, and Spencer 1983) for a step-by-step description of the adjustment process. A cursory review of the process follows.

Adjustment One: The first weighting adjustment involves the reciprocal of the probability of selection at the first interview. Specifically, this probability of selection is a function of the probability of selection associated with the household in which the respondent was located, as well as the subsampling (if any) applied to individuals identified in screening.

Adjustment Two: This process adjusts for differential response (cooperation) rates in both the screening phase and subsequent interviews. Differential cooperation rates are computed (and adjusted) on the basis of geographic location and group membership, as well as within-group subclassification.

Adjustment Three: This weighting adjustment attempts to correct for certain types of random variation associated with sampling as well as sample “undercoverage.” These ratio estimations are used to conform the sample to independently derived population totals.

Sampling Weight Readjustments: Sampling weights for the main survey are readjusted by NORC to account for noninterviews each survey year. The readjustments are necessitated by differential nonresponse and use base year sample parameters for their creation, employing a procedure similar to that described above. The only exception occurs in the final stage of post-stratification. Post-stratification weights in survey rounds two and above have been recomputed on the basis of completed cases in that year’s sample rather than the completed cases in the base year sample.

2.9 Practical Usage of Weights

The application of sampling weights varies depending on the type of analysis being performed. If tabulating sample characteristics for a single interview year in order to describe the population being represented (that is, compute sample means, totals, or proportions), researchers should weight the observations using the weights provided. For example, to estimate the average hours worked in 1987 by persons born in 1957 through 1964, simply use the weighted average of hours worked, where weight is the 1987 sample weight. These weights are approximately correct when used in this way, with item nonresponse possibly generating small errors. Other applications for which users may wish to apply weighting, but for which the application of weights may not correspond to the intended result include:

Samples Generated by Dropping Observations with Item Nonresponses: Often users confine their analysis to subsamples for which respondents provided valid answers to certain questions. In this case, a weighted mean will not represent the entire population, but rather those persons in the population who would have given a valid response to the specified questions. Item nonresponse because of refusals, don’t knows, or invalid skips is usually quite small, so the degree to which the weights are incorrect is probably quite small. In the event that item nonresponse constitutes only a small proportion of the data for variables under analysis, population estimates (that is, weighted sample means, medians, and proportions) would be reasonably accurate. However, population estimates based on data items that have relatively high nonresponse rates, such as family income, may not necessarily be representative of the underlying population of the cohort under analysis. For more information on item nonresponse in the NLSY79, see Chapter 5 of this User’s Guide.

Data from Multiple Waves: Because the weights are specific to a single wave of the study, and because respondents occasionally miss an interview but are contacted in a subsequent wave, a problem similar to item nonresponse arises when the data are used longitudinally. In addition, occasionally the weights for a respondent in different years may be quite dissimilar, leaving the user uncertain as to which weight is appropriate. In principle, if a user wished to apply weights to multiple wave data, weights would have to be recomputed based upon the persons for whom complete data are available. In practice, if the sample is limited to respondents interviewed in a terminal or end point year, the weight for that year can be used (for more information on weighting see the chapter on clustering adjustments in chapter 4 of this guide).

Regression Analysis: A common question is whether one should use the provided weights to perform weighted least squares when doing regression analysis. Such a course of action may not lead to correct estimates. If particular groups follow significantly different regression specifications, the preferred method of analysis is to estimate a separate regression for each group or to use dummy (or indicator) variables to specify group membership.

Users interested in calculating the population average effect of, for example, education upon earnings, should simply compute the weighted average of the regression coefficients obtained for each group, using the sum of the weights for the persons in each group as the weights to be applied to the coefficients. While least squares is an estimator that is linear in the dependent variable, it is nonlinear in explanatory variables, and so weighting the observations will generate different results than taking the weighted average of the regression coefficients for the groups. The process of stratifying the sample into groups thought to have different regression coefficients and then testing for equality of coefficients across groups using an F-test is described in most statistics texts.

Users uncertain about the appropriate grouping should consult a statistician or other person knowledgeable about the data set before specifying the regression model. Note that if subgroups have different regression coefficients, a regression on a random sample of the population would not be properly specified.

2.10 Design Effects

Because the samples are multi-stage, stratified random samples instead of simple random samples, respondents tend to come in geographic clusters and clusters of persons tend to be alike in a variety of ways for a variety of reasons. (For more information on the sampling and screening process, users are referred to sections 2.2 and 2.3 of this chapter.) For example, there may be cultural differences by locality or ecological differences in labor market conditions. Depending upon the degree of this homogeneity, the conventionally computed standard deviations for the variables, which assume a simple random sample, may be too small. However, by controlling the rate at which particular strata are sampled, multi-stage, stratified random samples can improve upon simple random samples. The ratio of the correct standard error to the standard error computed under the assumption of a simple random sample is known as the design effect. The technical sampling report for the NLSY79 (Frankel, Williams, and Spencer 1983) and its addendum (CHRR) provide design effects for the various strata.

A single design effect that can be broadly applied to regression analysis cannot be constructed. To illustrate the approximate size of design effects in regression analysis, a regression of rate of pay for the CPS job in 1979 was estimated using race, sex, marital status, and education as explanatory variables. Assuming each of the roughly 200 PSUs has the same number of respondents in the sample of 5,724 persons with observed wages, the design effect was calculated to be 1.52; that is, the true standard errors were larger than the naively computed standard errors by a factor of 1.52. When this exercise was repeated for rate of pay on the CPS job in 1986, the design effect had fallen to 1.37.

This reduction reflects the fact that mobility tends to mix the respondents more uniformly through the country, reducing the clustering of the sample. Many of the persons who started out in the same PSU will have moved to different areas and, hence, no longer share unobservable labor market conditions. These shared unobservable labor market conditions are likely responsible for the spatial correlation of the error terms which generate design effects. Thus, another advantage of longitudinal data is the lessening of design effects over time.

By examining the Geocode data for the NLSY79, it is possible to control for some of the environmental factors generating design effects or, if desired, to compute design effects based upon county or metropolitan area clusters which continue to be present. To facilitate study of design effects, scrambled PSU codes from the 1979 survey are available to persons ordering NLSY79 Geocode data.

Users interested in information on how to use the standard errors and design effects should refer to Appendix B, “Standard Errors and Design Effects,” at the end of this guide. The Technical Sampling Report and Technical Sampling Report Addendum also provide information on standard errors and design effects.

2.11 Confidentiality and Consent

Like all surveys, the National Longitudinal Surveys (NLS) rely on the cooperation of respondents to provide relevant, accurate, and timely information that researchers and policymakers can use to understand economic and social phenomena. At a minimum, securing cooperation requires survey administrators to explain clearly to potential respondents the uses of the survey and the importance of each respondent’s information to the success of the survey. Ethical survey practice entails more than just convincing members of the survey sample to participate, however. Sample members need to be informed about how their confidentiality will be protected, how their information will be used, whether participation is voluntary or mandatory, the estimated amount of time it will take to complete the survey, and any risks of participating.

Providing information about risks is particularly relevant for medical studies in which participants could suffer adverse reactions to drugs or treatments. Although the National Longitudinal Surveys have included health-related topics, information about these topics has been obtained only through questions asked of respondents, rather than through any medical exams or procedures. As such, NLSY79 respondents bear no risk of participating

After survey administrators provide this and other relevant information to potential respondents, those potential respondents can provide what is called their “informed consent” to participate.

The NLS program has established a variety of procedures for ensuring respondent confidentiality and obtaining informed consent. These procedures comply with Federal law and the policies and guidelines of the U.S. Office of Management and Budget (OMB), the U.S. Bureau of Labor Statistics (BLS), and the U.S. Census Bureau. This section describes the process of protecting respondent confidentiality and gaining informed consent in the NLSY79 and its associated Child and Young Adult surveys.

OMB procedures: OMB is responsible for setting overall statistical policy among Federal agencies. For example, OMB has established standards on collecting information about race and ethnicity, industry, occupation, and geographic location. OMB also has established standards on the manner and timing of data releases for such principal economic indicators as the gross domestic product, the national unemployment rate, and the Consumer Price Index. In addition, OMB sets standards on whether and how much respondents to Federal surveys can be paid for their participation, an issue of particular concern in the NLS program.

Another of OMB’s responsibilities is to review the procedures and questionnaires that Federal agencies use in collecting information from 10 or more respondents. Federal data collections reviewed by OMB include administrative data, such as the tax forms that the Internal Revenue Service requires individuals and corporations to complete. OMB also reviews all censuses and surveys that Federal agencies conduct, either directly or through contracts.

Surveys that are funded through Federal grants to universities and other organizations generally do not have to undergo this OMB review process unless the grantee in turn contracts with a Federal statistical agency such as the Census Bureau to collect the data. In place of OMB review, surveys funded through grants typically must undergo a competitive peer-review process established by the agency administering the grant, and that review process examines the procedures for maintaining respondent confidentiality and obtaining the informed consent of the participants. In addition, such surveys also typically are scrutinized by an institutional review board established at the grantee’s institution.

· The amount of time (and money, if any) that the agency collecting the information estimates respondents will spend to provide the requested information

· The agency’s efforts to reduce the burden on respondents of providing the information

· The purpose and necessity of the data collection, including whether it duplicates the objectives of other Federal data collections

· The ways in which the agency obtains informed consent from potential respondents to participate in the data collection

· The policies and procedures that the agency has established to ensure respondent confidentiality

· The statistical methods used to select representative samples, maximize response rates, and account for nonresponse

· The questionnaire itself, including the quality of its design and whether it includes questions that respondents may regard as sensitive

These OMB reviews are very thorough. From the time an agency prepares an OMB information collection request until the time OMB approves the data collection, the process typically takes 7 months or more and includes multiple layers of review within the agency and at OMB. These reviews are helpful in improving survey quality and ensuring that agencies treat respondents properly, both in terms of providing them with information about the data collection and its uses and protecting respondent confidentiality.

The review process also provides the general public with two opportunities to submit written comments about the proposed data collection. The agency conducting the data collection publishes a notice in the Federal Register describing the data collection and inviting the public to request copies of the information collection request, questionnaires, and other materials that the agency eventually will submit to OMB. The public is invited to submit written comments to the agency sponsoring the data collection within 60 days from the time the Federal Register notice is published. In the history of the NLS program, the public very rarely has submitted comments to BLS, but when comments are received, they are summarized in the information collection request that ultimately is submitted to OMB.

After the request has been submitted to OMB, the agency sponsoring the data collection then publishes a second notice in the Federal Register and invites the public to submit comments directly to OMB within 30 days. Again, in the history of the NLS program, the public very rarely, if ever, has submitted comments to OMB. Once OMB has received the information collection request, they have 60 days to review the package, ask follow-up questions, suggest changes (or, occasionally, insist upon changes) to the survey questionnaire or procedures, and ultimately grant approval.

After OMB grants approval, the sponsoring agency can begin contacting potential respondents and collecting information from them. The process of contacting potential NLS respondents begins with sending them an advance letter several weeks before interviews are scheduled to begin. The advance letter serves several purposes. The obvious purpose is to inform respondents that an interviewer will be contacting them soon, but BLS and the organizations that conduct the surveys for BLS also use the letter to thank respondents for their previous participation and to encourage them to participate in the upcoming round. Another important objective of the advance letter is to remind respondents that their participation is voluntary and to tell them how much time the interview is expected to take. The letter also explains to respondents how the data will be used and how respondents’ confidentiality will be protected by BLS and the organizations that conduct the surveys for BLS. An example of an advance letter is shown in figure 2.11.1.

Institutional review boards: In addition to OMB review, the NLSY79 is reviewed and approved by an institutional review board (IRB) at the institutions that manage and conduct the surveys under contract with BLS. Those institutions are The Ohio State University and the National Opinion Research Center (NORC) at the University of Chicago. BLS and OMB do not require these reviews; rather, the reviews are required under the policies of the universities. Obtaining approval from the IRBs involves completing a form signed by the Principal Investigator, providing a summary of the research project and submitting a description of the consent procedures and forms used in the survey. Additional documentation includes a copy of any materials used to recruit respondents, a detailed summary of the survey questionnaire, and any other information regarding the risks to humans of participating in the survey. OMB must review all data collections for the NLSY79.

Date

Respondent First and Last Name
Street Address
City, State Zip Code

Dear [Respondent First Name],

In a country increasingly committed to volunteerism, we on the National Longitudinal Survey of Youth 1979 (NLSY79) appreciate your continued participation in this study, which is sponsored by the Bureau of Labor Statistics of the U.S. Department of Labor. The economic, political, and military challenges faced by our country in recent months make the study even more important. Many leaders in business, education, and government believe that these circumstances could lead to long-term changes.

The time that you volunteer every two years provides policy makers and researchers in a variety of fields with a wealth of information about the experiences of your generation and changes in your life. You alone can make this contribution, as you cannot be replaced. Your participation is vital to the success of this important research project.

We remain extremely grateful to you for your continuing participation and look forward to speaking with you again in 2002. The interview will take about 60 minutes to complete. At the end of the interview, you will receive $40 in appreciation for your time. If you’d like, we’ll gladly provide you with a certificate confirming that you completed 5 hours worth of community service.

As always, the information you provide is protected under the Privacy Act and will be held in confidence to the full extent permitted by law. (Please see the Privacy Act statement on the back of this letter.) In case you have questions, the OMB control number for this survey is 1220-0109. Without this number, we would not be able to conduct this survey. (Please see the Disclosure Notice on the back of this letter.)

One of our interviewers from NORC at the University of Chicago will be contacting you in the coming weeks to set up a convenient appointment for your interview. In the meantime, if you have any questions about the study, please feel free to call us toll free at 1-877-853-5908 or send us an e-mail at NLS79@norcmail.uchicago.edu. More information about the NLS and the Bureau of Labor Statistics is available online at http://www.bls.gov/nls.

We look forward to talking with you soon! And again, thank you!

Sincerely,

Dr. Charles R. Pierret
Program Director
National Longitudinal Surveys

The NLSY79 project staff at The Ohio State University Center for Human Resource Research (CHRR) and at NORC obtain approval from their respective IRBs prior to the start of each round of data collection. Because each survey includes only an interview and no invasive medical procedures, the IRBs typically focus on respondent compensation, consent procedures, and confidentiality protections for special populations, such as incarcerated or disabled respondents. Prisons, schools, and other institutions in which NLSY79 sample members may reside often request the IRB approval statement and application as evidence that appropriate procedures are being followed and to judge whether to permit NLSY79 interviewers to have access to individuals for whom the institutions are responsible.

Federal laws: Two Federal laws govern policies and procedures for protecting respondent confidentiality and obtaining informed consent in the NLSY79 program: the Privacy Act of 1974 and the Confidential Information Protection and Statistical Efficiency Act (CIPSEA) of 2002. The Privacy Act and CIPSEA protect the confidentiality of participants in the NLSY79 and its associated Child and Young Adult surveys. CIPSEA protects the confidentiality of participants by ensuring that individuals who provide information to BLS under a pledge of confidentiality for statistical purposes will not have that information disclosed in identifiable form to anyone not authorized to have it.

In addition, CIPSEA ensures that the information respondents provide will be used only for statistical purposes. While it always has been the BLS policy to protect respondent data from disclosure through the Privacy Act and by claiming exemptions to the Freedom of Information Act, CIPSEA is important because it specifically protects data collected from respondents for statistical purposes under a pledge of confidentiality.

This law strengthens the ability of BLS to assure respondents that, when they supply information to BLS, their information will be protected. In addition, CIPSEA includes fines and penalties for any knowing and willful disclosure of specific information to unauthorized persons by any officer, employee, or agent of BLS. Since the enactment of the Trade Secrets Act and the Privacy Act, BLS officers, employees, and agents have been subject to criminal penalties for the mishandling of confidential data, and the fines and penalties under CIPSEA are consistent with those prior laws. CIPSEA now makes such fines and penalties uniform across all Federal agencies that collect data for exclusively statistical purposes under a pledge of confidentiality.

BLS policy requires that advance letters sent to potential respondents in these surveys include on the back of the letter the series of questions and answers about confidentiality and other survey topics shown in figure 2.11.2.

Figure 2.11.2 Confidentiality and Reporting Burden Information in the NLSY79 Advance Letter

WHY IS THIS STUDY IMPORTANT?

Thanks to your help, policymakers and researchers will have a better understanding of the work experiences, family characteristics, health, financial status, and other important information about the lives of people in your generation. This is a voluntary study, and there are no penalties for not answering questions. However, missing responses make it more difficult to understand the issues that concern people in your community and across the country. Your answers represent the experiences of hundreds of other people your age. We hope we can count on your participation again this year.

WHO AUTHORIZES THIS STUDY?

The sponsor of the study is the U.S. Department of Labor, Bureau of Labor Statistics. The study is authorized under Title 29, Section 2, of the United States Code. The Center for Human Resource Research at The Ohio State University and the National Opinion Research Center at the University of Chicago conduct this study under a contract with the Department of Labor. The U.S. Office of Management and Budget (OMB) has approved the questionnaire and has assigned 1220-0109 as the study’s control number. This control number expires on January 31, 2007. Without OMB approval and this number, we would not be able to conduct this study.

WHO SEES MY ANSWERS?

We want to reassure you that your confidentiality is protected by law. In accordance with the Confidential Information Protection and Statistical Efficiency Act of 2002, the Privacy Act, and other applicable Federal laws, the Bureau of Labor Statistics, its employees and agents, will, to the full extent permitted by law, use the information you provide for statistical purposes only, will hold your responses in confidence, and will not disclose them in identifiable form without your informed consent. All the employees who work on the survey at the Bureau of Labor Statistics and its contractors must sign a document agreeing to protect the confidentiality of your data. In fact, only a few people have access to information about your identity because they need that information to carry out their job duties.

Some of your answers will be made available to researchers at the Bureau of Labor Statistics and other government agencies, universities, and private research organizations through publicly available data files. These publicly available files contain no personal identifiers, such as names, addresses, Social Security numbers, and places of work, and exclude any information about the States, counties, metropolitan areas, and other, more detailed geographic locations in which survey participants live, making it much more difficult to figure out the identities of participants. Some researchers are granted special access to data files that include geographic information, but only after those researchers go through a thorough application process at the Bureau of Labor Statistics. Those authorized researchers must sign a written agreement making them official agents of the Bureau of Labor Statistics and requiring them to protect the confidentiality of survey participants. Those researchers are never provided with the personal identities of participants. The National Archives and Records Administration and the General Services Administration may receive copies of survey data and materials because those agencies are responsible for storing the Nation’s historical documents.

HOW MUCH TIME WILL THE INTERVIEW TAKE?

Based on preliminary tests, we expect the average interview to take about 60 minutes. Your interview may be somewhat shorter or longer depending on your circumstances. If you have any comments regarding this study or recommendations for reducing its length, send them to the Bureau of Labor Statistics, National Longitudinal Surveys, 2 Massachusetts Avenue NE., Washington, DC 20212.

In addition to these written questions and answers, survey interviewers are trained how to answer questions from respondents about how their privacy will be protected. Interviewers explain to potential respondents that all the employees who work on the surveys at BLS, NORC, and CHRR are required to sign a document stating that they will not disclose the identities of survey respondents to anyone who does not work on the NLS program and is therefore not legally authorized to have such information. In fact, no one at BLS has access to information about respondents’ identities, and only a few staff members at NORC and CHRR who need such information to carry out their job duties have access to information about respondents’ identities.

Interviewers also explain that the answers respondents provide will be made available to researchers at BLS and other government agencies, universities, and private research organizations, but only after all personal identifiers—such as names, addresses, Social Security numbers, and places of work—have been removed. In addition, the publicly available data files exclude any information about the States, counties, metropolitan statistical areas, and other, more detailed geographic locations in which respondents live, making it much more difficult to infer the identities of respondents.

Respondents are told that some researchers are granted special access to data files that include geographic information, but only after those researchers undergo a thorough application process at BLS and sign a written agreement making them official agents of BLS and requiring them to protect the confidentiality of respondents. In no case are researchers provided with information on the personal identities of respondents.

Finally, the reference in the questions and answers to the National Archives and Records Administration and the General Services Administration may be confusing to some potential respondents, because those Federal agencies are not involved in the administration of the surveys. Interviewers explain to respondents that NLS data and materials will be made available to those agencies because they are responsible for storing the Nation’s historical documents. The information provided to those agencies does not include respondents’ personal identities, however.

The organizations involved in the NLS program continuously monitor their security procedures and improve them when necessary. Protecting the privacy of NLS respondents entails considerable responsibilities for BLS, the organizations that conduct the surveys for BLS, and the researchers who use the data. Indeed, researchers in particular may become frustrated that they cannot obtain access to all the data that they want or that they must undergo a long review process at BLS to obtain some types of data. It is important to remember, however, that protecting respondent confidentiality must remain paramount. Any action that might jeopardize respondent confidentiality and erode the confidence of respondents could harm response rates in the NLS program and in other government or academic surveys. Thus, without the safeguards in place to protect respondent confidentiality, researchers would have far less data available to work with than they currently enjoy.

Contractors’ role in maintaining respondent confidentiality: BLS, NORC, and CHRR are responsible for following the Federal requirements and maintaining their own security procedures. As mentioned earlier, all officers, employees, and agents of BLS are required to sign agreements stating that they will not disclose the identities of survey respondents to anyone who does not work on the NLS program and is therefore not legally authorized to have such information. Each contractor has in place procedures to ensure that the data are secure at each point in the survey process. (See the Data Handling section of this chapter for more information.)

Like all contractor staff, field interviewers are agents of BLS and are required to sign the BLS agent agreement before working on the NLSY79. All interviewers also must undergo a background check when they are hired. Confidentiality is stressed during training and enforced at all times. Field interviewers receive specific instructions in their reference manuals to remind them of the appropriate procedures when locating or interacting with respondents or contacts.

At the end of each interview, interviewers ask respondents to provide information on family members, friends, or neighbors who can be contacted if the interviewers are unable to locate the sample member in a subsequent round of interviews. The interviewers then use those contacts to help in locating sample members who have moved. When contacting a sample member’s relatives, friends, or neighbors about the sample member’s whereabouts, interviewers never disclose the name of the survey they are conducting. They are instructed to maintain the confidentiality of any relative, friend, or neighbor who provides information about the sample member’s whereabouts.

Answering machines can pose problems when interviewers are contacting sample members because it is difficult to confirm that the interviewer is calling a sample member’s correct telephone number or that other household members will not hear the message. For those reasons, interviewers are instructed not to leave messages on answering machines.

When interviewers contact the appropriate household, they ask to speak with the sample member. Interviewers introduce themselves and state the purpose of the call by saying that they are from the National Opinion Research Center at the University of Chicago and are calling concerning a national survey. The name of the survey is not disclosed to anyone but the sample member.

Special situations: The NLSY79 is a general population survey and includes a variety of sample members with special circumstances, such as incarcerated individuals, respondents in the military, other institutionalized persons, disabled persons, those with limited English proficiency, and so forth.

Incarcerated respondents: Incarcerated respondents constitute the largest group requiring special accommodations. The first challenge with incarcerated respondents is contacting them to schedule an interview. NLS interviewers must contact the prison administration to arrange for an interview, but the interviewers cannot legally reveal to the prison administration that the prisoner previously had participated in the survey without first obtaining the written, informed consent of the prisoner to reveal that information.

User Notes: Data were incomplete for 2004 due to confidentiality concerns regarding inmate’s participation in the NLSY79. A protocol was established for round 22 of the NLSY79.

The process of obtaining prisoners’ consent begins by sending them a letter. The letter reminds prisoners that they have participated previously in a NORC survey, but, in case the mail is monitored by prison staff, the letter does not name the survey or BLS so as not to reveal the prisoner’s participation. The letter encourages the prisoner to participate in the upcoming round of the survey. It explains that NORC staff needs to set up an interview through the prison administration but that NORC cannot tell the prison administration about the prisoner’s participation without the prisoner’s informed consent. The letter then asks the prisoner to request a consent form by signing and dating an enclosed form letter and mailing it to NORC in a pre-addressed, postage-paid envelope. The letter reminds the prisoner that the mail at the institution may be monitored and explains that the consent form that NORC will send the prisoner will state the prisoner’s name and the name of the survey. The letter emphasizes that, by returning the enclosed form letter, prison management or staff may learn that the prisoner is a participant in the survey.

If the prisoner chooses to send the form letter to NORC, NORC then sends the prisoner a cover letter and a consent form that names the specific survey. The prisoner is asked to sign the consent form and mail it to NORC in a pre-addressed, postage-paid envelope. Once NORC has received the signed consent form, NORC staff can contact the prison to request permission to interview the prisoner and learn about any restrictions that the prison administration may impose.

If the prison administration permits an interview and a date and time have been scheduled for the interview, NORC mails another letter to the prisoner. This letter serves two purposes. First, it tells the prisoner when the interview will take place. Second, it informs the prisoner in writing that the interview very likely will be monitored by prison staff. That fact probably is obvious to any prisoner, but NLS staff feels that it is important to tell the prisoner in writing.

Once all of these steps are complete, the prisoner finally can be interviewed, but the NLS program takes additional steps to minimize the risk that prisoners might reveal illegal or illicit behavior in the presence of prison staff during the course of the interview.

During these portions of the survey, the typical protocol for a respondent who is not incarcerated involves the interviewer turning the laptop computer around to enable the respondent to read the questions to him or herself and enter the answers directly into the laptop computer without the interviewer knowing the responses. (In fact, the interviewer does not even know which questions the respondent answered). In some relatively low-security correctional facilities, such as some county jails and halfway houses, this protocol still would be possible. In higher security facilities, the prison administrators would not permit the prisoner to touch the computer, so the questions either would have to be read to the respondent or skipped altogether.

NLS program staff have identified the questions that could be considered even moderately sensitive or risky for the prisoner to answer out loud. Given this examination of these questions, the NLS program has adopted the following protocol for administering sensitive questions to prisoners:

At the very beginning of the interview, the interviewer will indicate in the survey instrument whether a respondent is in a correctional facility of any kind and, if so, whether the facility permits the prisoner to touch the laptop and enter responses to the self-administered questions. For Federal prisons, the interviewer assumes that the prisoner is not permitted to touch the laptop.

If the facility permits the prisoner to enter responses to the self-administered questions directly into the laptop, then the full set of questions, including all of the sensitive questions, would be administered.

If the facility does not permit the prisoner to enter responses directly into the laptop, or if the interview is conducted over the telephone rather than in person, all survey questions will be asked orally by the interviewer, but the instrument is programmed to skip sensitive questions in which the prisoner might be asked about illegal or illicit behavior

Military respondents: NLSY79 respondents who are in the military tend to be very cooperative and willing to participate in the surveys, but it sometimes can be difficult to locate and contact them, particularly if they are stationed outside the United States. It sometimes is necessary to seek the help of military or civilian staff in the Department of Defense to locate and contact military respondents, but NLS program staff first must obtain the military member’s written, informed consent to reveal to Department of Defense staff that he or she previously had participated in the survey and is willing to be contacted to participate in future rounds of the survey.

Respondents with limited English proficiency: Some respondents lack fluency in English and are more comfortable using another language. It is not possible to accommodate all of the different languages other than English that respondents might speak, but the NLSY79 historically has made special arrangements for respondents and their parents who speak Spanish, the most commonly spoken language other than English among respondents. NORC staff members translate advance letters and other informational materials into Spanish to enable respondents and the parents of minor respondents to provide their informed consent based on information that is written in the language that they understand best. Survey questionnaires also have been translated into Spanish to ensure that the surveys are administered consistently, an alternative much preferable to having Spanish-speaking interviewers translate the English-language questionnaire during the interview. The first 20 rounds of the NLSY79 included a Spanish version of the questionnaire, but, because the number of respondents who speak only Spanish has continued to decline, it no longer is cost-effective to continue programming a computerized Spanish questionnaire. For that reason, Spanish questionnaires are not used starting with round 21 (2004) of the NLSY79. Advance letters and other informational materials still are available in Spanish, however.

Sensitive subjects: The NLSY79 has included questions on income and assets, religion, relationships with parents and other family members, sexual experiences, abortion, drug and alcohol use, criminal activities, homelessness, runaway episodes, and other topics that are potentially sensitive for respondents to discuss. Respondents are advised at the start of the interview that they can choose not to answer any questions that they prefer not to answer. During training, interviewers undergo exercises to teach them how to allay the concerns of respondents about answering sensitive questions and encourage them to respond. Interviewers are instructed not to coerce respondents into answering questions that they prefer not to answer, however.

All questions in the NLSY79 are read to the respondent by an interviewer. The respondent then provides an answer, and the interviewer records that answer on a laptop computer. For especially sensitive questions, some respondents might be reluctant to answer truthfully—or at all—if they have to tell an interviewer their answers, even though interviewers can face criminal and civil penalties if they disclose the respondents’ identities or answers to anyone not authorized to receive that information.

Guidelines for e-mailing sample members: At the end of each interview, respondents are asked to provide information that will help interviewers contact them during subsequent rounds of the surveys. In addition to the information collected about relatives, friends, or neighbors, interviewers also obtain the e-mail addresses of sample members who have them. During round 20 of the NLSY79 (conducted during 2002), the NLS contractors began using e-mail as a means to contact a small number of sample members who were hard to reach by other means. The following guidelines were enacted to ensure confidentiality:

· The name of the survey is not contained in the subject line or text of the e-mail message. Some sample members may share the use of an e-mail address with other household members, so the survey name is omitted from the message to prevent other household members from learning the specific name of the survey.

· E-mail is sent from one NORC address. Field interviewers are not permitted to use their individual e-mail accounts to contact sample members.

Respondents knowing respondents: One feature of the sample design in the NLSY79 is that there often are multiple respondents within the same original household, either siblings or, occasionally, spouses. It obviously is not possible in these cases to prevent family members from knowing that a relative is in the survey sample, but interviewers take steps to ensure that each respondent’s answers remain private and are not revealed to other family members.

Consent from NLSY79 respondents: Respondents are able to review the confidentiality and consent information presented in the advance letter. The respondent gives verbal consent to participate at the beginning of the interview.

Data handling: An important part of maintaining respondent confidentiality is the careful handling and storage of data. Steps taken by BLS, CHRR, and NORC to ensure the confidentiality of all respondents to the NLSY79 include maintaining secure networks, restricting access to geographic variables, and topcoding income and asset values.

Network security: The data that are stored and handled at each NLSY79 organization’s site are done so with maximum security in place. During data collection, transmission, and storage, password protection and encryption are used to secure the data. Standard protocols for network security are followed at each organization’s site. Detailed information about these arrangements is not provided to the public to prevent anyone from circumventing these safeguards.

Restricting access to geographic information: Geographic information about NLSY79 respondents is available only to researchers who are designated agents of BLS. These researchers must agree in writing to adhere to the BLS confidentiality policy, and their projects must further the mission of BLS and the NLSY79 program to conduct sound, legitimate research in the social sciences. Applicants must provide a clear statement of their research methodology and objectives and explain how the geographic variables are necessary to meet those objectives. For more information about obtaining access to geographic variables in the NLSY79, see the NLS Web site at www.bls.gov/nls.

Topcoding of income and asset variables: Another step taken to ensure the confidentiality of NLSY79 respondents who have unusually high income and asset values is to “topcode” those values in NLSY79 data sets. Values that exceed a certain level are recoded so that they do not exceed the specified level. In each survey round, income and asset variables that include high values are identified for topcoding. For example, the wage and salary income variable usually is topcoded, but variables indicating the amount received from public assistance programs are not. Notes in the codebooks for topcoded income and asset variables provide more information about the exact calculations used to topcode each variable.

	Designated for Interviewing	Interviewed Initial Survey Year
Total Cohort	14574	12686	87%
Cross-Sectional Sample¹	6812	6111	90%
Supplemental Sample¹	5969	5295	89%
Military Sample	1793	1280	72%

¹ As determined through the household screening.

Survey Year(s)	Fielding Period
1979-80	January-August
1981-82	January-July
1983-85	January-June
1986	February-July
1987	March-October
1988-91	June-December
1992	May-December
1993	June-November
1994	June-December
1996	April-October
1998	March-September
2000	April 2000-January 2001
2002	January-December
2004	January 2004-February 2005
2006	January 2006–March 2007

Year	Number of Phone Interviews	Percent of Total Interviews	Year	Number of Phone Interviews	Percent of Total Interviews
1979	548	4.4	1990	1317	12.6
1980	648	5.3	1991	1241	13.8
1981	654	5.4	1992	1164	12.9
1982	1054	8.7	1993¹	-	-
1983	324	2.6	1994¹	-	-
1984	646	5.3	1996	1042	12.1
1985	953	8.7	1998	2069	24.6
1986	929	8.7	2000	2613	32.5
1987	8998	85.8	2002	5407	70.0
1988	920	8.8	2004	6497	82.8
1989	1518	14.3	2006	6543	85.6

¹Questions identifying whether interview was conducted by telephone were not included in the 1993 and 1994 surveys.

Year	Percent	Number	Year	Percent	Number
1979	100%	9964	1990	76.7%	7642
1980	96.0%	9571	1991	75.5%	7521
1981	94.3%	9395	1992	74.2%	7396
1982	92.7%	9234	1993	73.2%	7291
1983	91.6%	9125	1994	71.8%	7153
1984	89.7%	8942	1996	69.6%	6935
1985	87.5%	8721	1998	66.9%	6664
1986	85.0%	8472	2000	63.3%	6310
1987	82.3%	8203	2002	60.3%	6004
1988	79.9%	7957	2004	57.6%	5736
1989	78.5%	7819	2006	55.6%	5538

Race¹	# of Interviewed Respondents		Racial Composition (percentage)		Retention (2004) as % of 1979	Number of Deaths as of 2006
Race¹	1979	2006	1979	2006	Retention (2004) as % of 1979	Number of Deaths as of 2006
Hispanic or Latino	1961	1490	19.7	19.5	73.1	69
Black	3001	2385	30.1	31.1	78.9	159
Non-Black/Non-Hispanic	5002	3783	50.2	49.4	77.0	142

¹ See section on "Race, Ethnicity & Nationality" in this guide for details on race classifications.

Chapter 2: Sample Design & Fielding Procedures

2.1 Sample Design

2.2 Screening

2.3 Sampling Process

Figure 2.3.1 Number of Respondents Born Each Month by Birth Year ¹

Table 2.3.1 Base Year Interview Completion: NLSY79

Table 2.3.2 NLSY79 Military Respondents Interviewed in 1979 by Sex, Race & Military Branch

2.4 Interview Schedule & Fielding Periods

Table 2.4.1 NLSY79 Fielding Periods

2.5 Interview Methods & Target Universe

Table 2.5.1 Percent of NLSY79 Interviews Conducted by Telephone, 1979-2006

Retention vs. Response Rates

Table 2.5.2 Sample Sizes & Retention Rates by Sample Type: NLSY79

Table 2.5.3 Response Rates (Excluding Deceased Sample Members) by Sample Type: NLSY79
NOTE: This table was revised on 3/20/07.

2.6 Reasons for Noninterview

Table 2.6.1 Reasons for Noninterview: NLSY79 1979-2006

Table 2.6.2 Reasons for Noninterview by Sex: NLSY79 1980-2006

Table 2.6.3 Reasons for Noninterview by Race/Ethnicity: NLSY79 1980-2006

Table 2.6.4 Reasons for Noninterview by Sample Type: NLSY79 1980-2006

2.7 Sample Representativeness & Attrition

Table 2.7.1 Percentage of NLSY79 Respondents, Excluding Dropped Respondents, Who Answered Every Survey: 1979-2006

Table 2.7.2 Cohort Characteristics by Race: 1979-2006

Table 2.7.3 Number of Interviews Respondents Completed out of 22 Surveys by Sex: NLSY79 1979-2006

Table 2.7.4 Number of Interviews Respondents Completed out of 22 Surveys by Race: NLSY79 1979-2006

Table 2.7.5 Number of Interviews Respondents Completed out of 22 Surveys by Sample Type: NLSY79 1979-2006

2.8 Sample Weights

2.9 Practical Usage of Weights

2.10 Design Effects

2.11 Confidentiality and Consent

References

	Cross-Sectional Sample			Supplemental Sample			Military Sample			Total Sample
Year	# Response	Total Deceased	Rate	# Response	Total Deceased	Rate	# Response	Total Deceased	Rate	# Response	Total Deceased	Rate
1979	6,111	0	-	5,295	0	-	1,280	0	-	12,686	0	-
1980	5,873	4	96.2	5,075	5	95.9	1,193	0	93.2	12,141	9	95.8
1981	5,892	15	96.7	5,108	14	96.7	1,195	0	93.4	12,195	29	96.3
1982	5,876	24	96.5	5,036	19	95.5	1,211	1	94.7	12,123	44	95.9
1983	5,902	27	97.0	5,093	26	96.7	1,226	4	96.1	12,221	57	96.8
1984	5,814	30	95.6	5,040	33	95.8	1,215	4	95.2	12,069	67	95.6
1985	5,751	36	94.7	4,957	43	94.4	186¹	0	92.5	10,894¹	79	94.5
1986	5,633	43	92.8	4,839	51	92.3	183	1	91.5	10,655	95	92.6
1987	5,538	51	91.4	4,768	56	91.0	179	3	90.4	10,485	110	91.2
1988	5,513	56	91.0	4,777	68	91.4	175	3	88.4	10,465	127	91.2
1989	5,571	60	92.1	4,853	78	93.0	181	3	91.4	10,605	141	92.5
1990	5,498	67	91.0	4,755	82	91.2	183	3	92.4	10,436	152	91.1
1991	5,556	75	92.0	3,281²	65	91.5	181	4	91.9	9,018²	144	91.9
1992	5,553	81	92.1	3,280	71	91.6	182	4	92.4	9,015	156	91.9
1993	5,537	90	92.0	3,293	83	92.3	181	4	91.9	9,011	177	92.1
1994	5,457	104	90.8	3,256	96	91.6	178	4	90.4	8,891	204	91.1
1996	5,290	129	88.4	3,171	109	89.5	175	5	89.3	8,636	243	88.8
1998	5,159	152	86.6	3,065	118	86.7	175	5	89.3	8,399	275	86.7
2000	4,949	170	83.3	2,921	136	83.1	163	7	84.0	8,033	313	83.2
2002	4,775	188	80.6	2,792	151	79.7	157	7	80.9	7,724	346	80.3
2004	4,686	221	79.6	2,818	171	81.0	157	7	80.9	7,661	399	80.1
2006	4630	252	79.0	2862	197	82.8	162	7	83.5	7654	456	80.5

Note: Response rate is defined as the percentage of base-year respondents remaining eligible and not known to be deceased who were interviewed in a given survey year.
¹ A total of 201 military respondents were retained from the original sample of 1,280; 186 of the 201 participated in the 1985 interview. The total number of NLSY79 civilian and military respondents eligible for interview (including deceased respondents) beginning in 1985 was 11,607.
²The 1,643 economically disadvantaged nonblack/non-Hispanic male and female members of the supplemental subsample were not eligible for interview as of the 1991 survey year. The total number of NLSY79 civilian and military respondents eligible for interview (including deceased respondents) beginning in 1991 was 9,964.

Total Sample			Cross Sectional Sample			Supplemental Sample			Military Sample
# of Surveys¹	# who Completed	Cumul. Percent	# of Surveys¹	# who Completed	Cumul. Percent	# of Surveys¹	# who Completed	Cumul. Percent	# of Surveys¹	# who Completed	Cumul. Percent
22	5538	55.6	22	3564	58.3	22	1882	51.5	22	92	45.8
21	1200	12	21	643	10.5	21	531	14.5	21	26	12.9
20	661	6.6	20	354	5.8	20	292	8.0	20	15	7.5
19	474	4.8	19	259	4.2	19	199	5.5	19	16	8.0
18	389	3.9	18	227	3.7	18	148	4.1	18	14	7.0
17	256	2.6	17	161	2.6	17	84	2.3	17	11	5.5
16	251	2.5	16	153	2.5	16	90	2.5	16	8	4.0
15	161	1.6	15	105	1.7	15	53	1.5	15	3	1.5
14	137	1.4	14	87	1.4	14	45	1.2	14	5	2.5
13	115	1.2	13	76	1.2	13	39	1.1	13	0	0.0
12	94	0.9	12	58	1.0	12	33	0.9	12	3	1.5
11	85	0.9	11	49	0.8	11	36	1.0	11	0	0.0
10	78	0.8	10	48	0.8	10	30	0.8	10	0	0.0
9	85	0.8	9	48	0.8	9	37	1.0	9	0	0.0
8	75	0.8	8	46	0.8	8	28	0.8	8	1	0.5
7	82	0.8	7	57	0.9	7	23	0.6	7	2	1.0
6	73	0.7	6	43	0.7	6	29	0.8	6	1	0.5
5	58	0.6	5	43	0.7	5	14	0.4	5	1	0.5
4	42	0.4	4	20	0.3	4	20	0.6	4	2	1.0
3	30	0.3	3	20	0.3	3	10	0.3	3	0	0.0
2	39	0.4	2	23	0.4	2	15	0.4	2	1	0.5
1	41	0.4	1	27	0.4	1	14	0.4	1	0	0.0
Total	9964	100	Total	6111	100	Total	3652	100	Total	201	100

Note: Universe excludes the 1,079 members of the military subsample and the 1,643 members of the economically disadvantaged, non-black/non-Hispanic oversample dropped from interviewing; it includes the remaining 9,964 eligible members.
¹Surveys completed in any year, not necessarily consecutive survey years.

Chapter 2: Sample Design & Fielding Procedures

2.1 Sample Design

2.2 Screening

2.3 Sampling Process

Figure 2.3.1 Number of Respondents Born Each Month by Birth Year 1

Table 2.3.1 Base Year Interview Completion: NLSY79

Table 2.3.2 NLSY79 Military Respondents Interviewed in 1979 by Sex, Race & Military Branch

2.4 Interview Schedule & Fielding Periods

Table 2.4.1 NLSY79 Fielding Periods

2.5 Interview Methods & Target Universe

Table 2.5.1 Percent of NLSY79 Interviews Conducted by Telephone, 1979-2006

Retention vs. Response Rates

Table 2.5.2 Sample Sizes & Retention Rates by Sample Type: NLSY79

Table 2.5.3 Response Rates (Excluding Deceased Sample Members) by Sample Type: NLSY79 NOTE: This table was revised on 3/20/07.

2.6 Reasons for Noninterview

Table 2.6.1 Reasons for Noninterview: NLSY79 1979-2006

Table 2.6.2 Reasons for Noninterview by Sex: NLSY79 1980-2006

Table 2.6.3 Reasons for Noninterview by Race/Ethnicity: NLSY79 1980-2006

Table 2.6.4 Reasons for Noninterview by Sample Type: NLSY79 1980-2006

2.7 Sample Representativeness & Attrition

Table 2.7.1 Percentage of NLSY79 Respondents, Excluding Dropped Respondents, Who Answered Every Survey: 1979-2006

Table 2.7.2 Cohort Characteristics by Race: 1979-2006

Table 2.7.3 Number of Interviews Respondents Completed out of 22 Surveys by Sex: NLSY79 1979-2006

Table 2.7.4 Number of Interviews Respondents Completed out of 22 Surveys by Race: NLSY79 1979-2006

Table 2.7.5 Number of Interviews Respondents Completed out of 22 Surveys by Sample Type: NLSY79 1979-2006

2.8 Sample Weights

2.9 Practical Usage of Weights

2.10 Design Effects

2.11 Confidentiality and Consent

References

Figure 2.3.1 Number of Respondents Born Each Month by Birth Year ¹

Table 2.5.3 Response Rates (Excluding Deceased Sample Members) by Sample Type: NLSY79
NOTE: This table was revised on 3/20/07.