| On this page: | On separate pages: Chapter 2 part 2 Chapter 2 part 3 |
The original NLS of Mature Women sample was designed to represent the civilian noninstitutionalized population of the United States ages 30-44 as of March 31, 1967, at the time of the initial survey. The cohort is represented by a multi-stage probability sample drawn by the Census Bureau from 1,900 primary sampling units (PSUs) that had originally been selected from the nation's counties and cities for the experimental Monthly Labor Survey conducted between early 1964 and late 1966. A primary sampling unit consists of Standard Metropolitan Statistical Areas (SMSAs), counties (or parishes in some states), parts of counties, and independent cities. A total of 235 sample areas, comprising 485 counties and independent cities, were chosen to represent every state and the District of Columbia. From the sample areas, 235 strata were created of one or more PSUs that were relatively homogeneous according to socioeconomic characteristics. Within each stratum, a single PSU was selected to represent that stratum. Finally, within each PSU, a probability sample of housing units was selected to represent the civilian noninstitutionalized population. Because the addresses for the sample frame came from the 1960 Census, respondents are covered by Title 13 confidentiality restrictions. Variables that are linked to geographic residence, including county and state, are available for use at Census Data Centers (see www.ces.census.gov for more information).
As dictated by the above requirements, the initial sample of about 42,000 housing units for all four NLS Original Cohorts was selected and screening interviews took place in March and April of 1966. Of this number, about 7,500 units were found to be either vacant, occupied by persons whose usual residence was elsewhere, changed from residential use, or demolished. On the other hand, about 900 additional units were found created within existing living space or changed from what had been nonresidential space. A total of 35,360 housing units were available for interview, from which usable information was collected for 34,662 households, for a completion rate of 98.0 percent.
The original plan called for using the initial screening to select all four NLS Original Cohorts. However, after the sample members for the Older Men were chosen, the sample was rescreened in September 1966 before the initial interview of the Young Men. This decision was made because a seven-month delay between the screening and first interview seemed inordinate due to the mobility of Young Men in their late teens and early twenties. To increase efficiency, it was decided to stratify the sample for the rescreening by the presence or absence of a 14- to 24-year-old male in the household. The probability was high that a household that contained a 14- to 24-year-old in March would also have such a member in September. However, to insure that the sample also represented persons who had moved into sample households in the intervening period, a sample of addresses that previously had no 14- to 24-year-old males was also included in the rescreening operation. Since a telephone number had been recorded for most households at the time of the initial screening interview, every attempt was made to complete the short screening interview by telephone. The sample of households from the initial screening, supplemented with information from the rescreening, was subsequently used to obtain the two samples of women ages 30-44 and 14-24 for the Mature Women and Young Women cohorts (Parnes et al. 1970; Shea et al. 1971).
| User Notes: During the screening process a large number of multiple respondent households were designated for interview; more than half of respondents in the Mature Women, Young Women, and Young Men cohorts and one-third of respondents in the Older Men cohort originated from multiple respondent households (i.e., households in which at least one other NLS respondent resided). For more information on multiple respondent households and on the types of relationships that existed between respondent pairs (e.g., spouse, sibling, etc.), see the "Household Composition" section of this guide. |
Following the initial household interview and rescreening operation, 5,393 women ages 30-44 as of March 31, 1967, were designated to be interviewed for the Mature Women cohort. The sample was designed to provide approximately 5,000 respondents--about 1,500 nonwhites and 3,500 whites. The women were sampled differentially within four strata: whites in predominantly white enumeration districts (EDs) , non-whites in predominantly non-white EDs, whites in predominantly non-white EDs, and non-whites in predominantly white EDs. An enumeration district is a geographical area considered to be an appropriate size for an interviewer to complete all necessary interviews within a prescribed time frame. To provide separate reliable statistics for black respondents, the sample design called for oversampling of blacks at twice the expected rate in the total population. The sampling rate of households in predominantly non-white EDs was between three and four times that for households in predominantly white EDs in order to meet this survey requirement. During the first survey in 1967, 5,083 (94.3 percent) of the designated women were interviewed.
In the initial survey plan, respondents from each of the four Original Cohorts were to be interviewed yearly over a five-year period. However, due to cost considerations, it was decided after the second survey of the Older Men to survey the two older groups (Older Men and Mature Women) biennially rather than annually. In order to permit a survey at the end of the five-year period, Mature Women respondents were interviewed in both 1971 and 1972. A decision was made at the end of the first five-year period to continue the interviews for another five years because of the usefulness of these data and the relatively small sample attrition. At this point, the interviewing pattern changed from a biennial personal interview to a 2-2-1 schedule; each respondent was contacted by phone approximately every two years, then again in person one year after the second phone interview. The 2-2-1 schedule was continued through 1987 when the decision was made to conduct a personal interview every other year. However, the implementation of the biennial schedule was interrupted by the 1990 decennial Census. The scheduled 1990 Young Women survey was pushed back to 1991; the scheduled 1991 Mature Women survey was conducted in 1992. The scheduled 1994 Mature Women survey was then delayed until the 1995 CAPI/CATI administration. Table 2.4.1 depicts the years in which the cohort was surveyed, the fielding period, the percent of the cohort interviewed, and the type of interview utilized. Users should note that, in years during which the survey was conducted in person, some interviews were administered by telephone when necessary.
| Year | Primary type of interview1 | Fielding period | Total interviewed | Retention rate2 | Response rate, living sample members only3 |
| 1967 | Personal | May-July | 5083 | 100.0% | 100.0% |
| 1968 | May-July | 4910 | 96.6 | 97.0 | |
| 1969 | Personal | May-July | 4712 | 92.7 | 93.3 |
| 1971 | Personal | April-June | 4575 | 90.0 | 91.0 |
| 1972 | Personal | April-June | 4471 | 88.0 | 89.3 |
| 1974 | Telephone | April-June | 4322 | 85.0 | 86.7 |
| 1976 | Telephone | April-June | 4172 | 82.1 | 84.2 |
| 1977 | Personal | April-June | 3964 | 78.0 | 80.3 |
| 1979 | Telephone | April-June | 3812 | 75.0 | 77.8 |
| 1981 | Telephone | April-June | 3677 | 72.3 | 75.8 |
| 1982 | Personal | July-September | 3542 | 69.7 | 73.4 |
| 1984 | Telephone | April-June | 3422 | 67.3 | 71.8 |
| 1986 | Telephone | July-September | 3335 | 65.6 | 71.1 |
| 1987 | Personal | July-September | 3241 | 63.8 | 69.5 |
| 1989 | Personal | June-August | 3094 | 60.9 | 67.6 |
| 1992 | Personal | October-December | 2953 | 58.1 | 66.6 |
| 1995 | Personal | June-September | 2711 | 53.3 | 63.5 |
| 1997 | Personal | July-September | 2608 | 51.3 | 63.7 |
| 1999 | Personal | June-August | 2467 | 48.5 | 62.4 |
| 2001 | Personal | June-August | 2318 | 45.6 | 61.8 |
| 2003 | Personal | June-August | 2237 | 44.0 | 62.2 |
| 1 Even in years during which the survey was conducted in person, some interviews were administered by telephone when that was the best way to complete a case. |
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| 2 Retention rate is defined as the percent of base-year sample members who were interviewed in any
given
survey year. Included in the calculations are deceased and institutionalized sample members, as well as those serving in the military. The base-year number of sample members used in these calculations includes those who in later years died, became institutionalized, or joined the military. |
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| 3 This retention rate excludes sample members known to be deceased in each survey year. | |||||
| Year1 | Personal | Telephone | Not available | Interviewed | Not interviewed | ||||
| 1974 | 917 | 21.2% | 3,326 | 77.0% | 79 | 1.8% | 4,322 | 761 | 15.0% |
| 1976 | 612 | 14.7 | 3,560 | 85.3 | 0 | -- | 4,172 | 911 | 17.9 |
| 1979 | 472 | 12.4 | 3,328 | 87.3 | 12 | 0.3 | 3,812 | 1,271 | 25.0 |
| 1981 | 383 | 10.4 | 3,294 | 89.6 | 0 | -- | 3,677 | 1,406 | 27.7 |
| 1984 | 354 | 10.3 | 3,063 | 89.5 | 5 | 0.1 | 3,422 | 1,661 | 32.7 |
| 1986 | 366 | 11.0 | 2,948 | 88.4 | 21 | 0.6 | 3,335 | 1,748 | 34.4 |
| 1989 | 2,567 | 83.0 | 513 | 16.6 | 14 | 0.5 | 3,094 | 1,989 | 39.1 |
| 1992 | 2,298 | 77.8 | 602 | 20.4 | 53 | 1.8 | 2,953 | 2,130 | 41.9 |
| 1995 | 2,144 | 79.1 | 536 | 19.8 | 31 | 1.1 | 2711 | 2,372 | 46.7 |
| 1999 | 1,523 | 61.7 | 813 | 33.0 | 131 | 5.3 | 2,467 | 2,616 | 51.5 |
| 2001 | 1,376 | 59.4 | 883 | 38.1 | 59 | 2.5 | 2,318 | 2,765 | 54.4 |
| 2003 | 1,299 | 58.1 | 836 | 37.4 | 102 | 4.5 | 2,237 | 2,846 | 56.0 |
| NOTE: Respondents who conducted part of an interview in person and part over the telephone are included in the telephone category. | |||||||||
| 1 The years with available mode of interview data are listed. Missing years do not have this data recorded. | |||||||||
User Notes: Although each of the personal interviews contains data of roughly the same degree of completeness, data gathered during the early PAPI-year interviews conducted primarily via telephone were not meant to update the longitudinal record of a respondent. Rather, the telephone interviews were intended to obtain a brief update of information on each respondent and to maintain sufficient contact so that the lengthier personal interview could be completed. The combination of fluctuating fielding periods and type of interview (i.e., personal, mail, or phone) may affect not only the probability of reinterview but also the reference periods of time-related questions. There is another source of inconsistency with respect to time references. A given year's survey instrument may use the previous calendar year as a reference period for some questions, while other questions will collect data for the period since the last interview. Income data, for example, may be collected for the calendar year, corresponding to the time frame for a respondent's tax records; employment data are usually collected for the period since the last interview. In most cases the variable titles will indicate the time period covered. |