Chapter 2 continued:  Sample Design and Attrition

• 2.5  Interview Methods

• 2.6 Eligible Sample & Reasons for Noninterview

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2.5  Interview Methods

Before each survey period begins, the Census Bureau generates lists of respondents to be interviewed and distributes them to 12 regional offices.  Current addresses and contact information are generated from data collected during the last interview and through a postal check conducted by Census, and cases are assigned to interviewers who live in the same geographic area as the respondent.  Interviewers then receive copies of the questionnaire (or a laptop computer for CAPI/CATI interviews), respondents’ Household Record Cards, and flashcard and information booklets.

In each survey round, interviewers are responsible for contacting each respondent in their caseload and for using additional local level resources to locate those respondents who have moved since the last interview.  Respondents who have moved outside the geographic district of their original interviewer are assigned to another unless there are no personnel nearby.  In the latter event, an effort is made to interview the respondent by telephone.

Each respondent to be interviewed is sent various materials designed to encourage continued participation.  Advance letters thanking respondents for taking part in the interviews and informing them of the coming survey are mailed prior to each interview period.  Fact sheets highlighting recent research findings from each cohort’s survey data are also provided.  Respondents who initially refuse to participate in a survey are sent letters and some additional materials by the regional offices designed to encourage their continued participation and are once again contacted by local level interviewers to secure the interview.

While the type of survey, personal or telephone, determines the chief mode of contact, an alternate contact method is used for certain respondents.  During a personal survey, for example, those respondents who live long distances from the Census interviewer’s base of operation or those for whom the Census supervisor has decided that another contact method is warranted are contacted by telephone.  Although survey instruments are written in English only, multilingual interpreters are made available by the regional offices to interviewers who need them.

In 1995, respondents in the two women’s cohorts were interviewed during the same time period; a single computer-assisted personal interview (CAPI) or computer-assisted telephone interview (CATI) replaced the paper-and-pencil interview (PAPI) instruments used during the previous interviews.  While data were collected simultaneously for the two cohorts, they were released separately by cohort.  This CAPI/CATI interview has continued on a biennial basis.

The average length of an interview varies depending on the type conducted, with personal PAPI interviews lasting 50–60 minutes, CAPI interviews lasting about 70 minutes, and CATI interviews averaging 20–25 minutes.  No stipends have been paid to Original Cohort respondents for their participation.

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2.6 Eligible Sample & Reasons for Noninterview

In general, respondents selected for interviewing each year are those who participated in the initial survey and who are alive, residing within the United States at the interview date, noninstitutionalized, and not members of the Armed Forces.  However, the criteria used to select the eligible sample—respondents whom the Census Bureau attempts to interview in a given round—have varied somewhat over the years.

Beginning in 1969, any respondent who had refused to be interviewed during a previous round was dropped from the eligible sample.  Beginning in 1971, respondents were also dropped from the eligible sample if they had not been interviewed in two consecutive surveys for reasons other than death or refusal (for example, respondents who could not be located or contacted during the field period—those with ‘Reason for Noninterview’ codes of 1, 2, 3, 4, 5, 6, 8, or 11). The User Notes after Table 2.6.3 describe how dropped respondents can be identified.  In 1983, the Census Bureau ceased dropping individuals for these two reasons, and in 1985 attempts were made to reinterview some of the dropped individuals.  The following selection criteria determined which respondents would be reinterviewed (see Table 2.6.1 for examples of each case):

1)      If the respondent refused to be interviewed in 1972 or earlier, she was not eligible to be reinterviewed.  See example respondent 1 in the table below.

2)      If the respondent missed her second consecutive survey in 1972 or earlier, she was not eligible to be reinterviewed.  See example respondent 2.

3)      If the respondent refused an interview in 1973 or later, survey staff attempted to reinterview her in 1985.  If the respondent was interviewed in 1985, she rejoined the eligible sample for all subsequent surveys.  If she was not interviewed in 1985, she remained ineligible for all subsequent surveys.  See example respondent 3.

4)      If the respondent was interviewed in 1971 and subsequently dropped due to two consecutive noninterviews, she was eligible for reinterview in 1985.  If the respondent was interviewed in 1985, she rejoined the eligible sample for all subsequent surveys.  If she was not interviewed in 1985, she remained ineligible for all subsequent surveys.  See example respondent 4.

5)      If the respondent first refused to participate in 1982, she was not eligible to participate in 1983 but rejoined the eligible sample in 1985.  She remained in the eligible sample regardless of her interview status in 1985.  See example respondent 5 in the table.

6)      If the respondent was not interviewed in 1981 and 1982 for reasons other than death or refusal, she was never dropped from the sample.  She remained eligible for all subsequent rounds regardless of prior participation.  See example respondent 6.

Table 2.6.1  Selection of Respondents Eligible for 1985 Survey

Table 2.6.2 below depicts reasons for exclusion from the eligible sample and the years each applied; Tables 2.6.4 and 2.6.5 later in this section present reasons for noninterview across survey years.

Table 2.6.2  Reasons for Exclusion from the Eligible Samples

Each survey year, CHRR creates a cumulative ‘Reason for Noninterview’ variable for the full sample of respondents.  Variable reference numbers for this series from 1969 to 2001 are:  R00854., R01453., R02525., R03353., R04171., R05195., R05483., R05874., R07099., R07564.10, R08032.10, R09473.10, R10628.10, R11092.10, R12327.10, R13652.10, R16012., R34981., R42670., and R63203.  This created variable is a combination of (1) the noninterview reasons provided by Census for the subset of respondents designated as eligible for interview in that survey year and (2) the reason for noninterview assigned during a previous survey to out-of-scope respondents.  In 1982, CHRR began releasing an additional variable reflecting the reasons for noninterview for only those respondents with whom interviews were attempted that year (e.g., R07564.).  The number of respondents that Census designates as eligible for interviewing fluctuates by survey year.

Instructions to interviewers on how to code a respondent’s reason for noninterview appear within the Interviewer’s Reference Manuals (or Field Representative’s Manuals).  The set of noninterview coding categories present during the initial survey years has been supplemented over the years with additional reasons for noninterview, and the meanings of existing categories have been refined.  Table 2.6.3 presents the raw coding categories present on the public data files and specifies the survey years during which each category was utilized. 

Table 2.6.3  Conceptual & Raw Coding Categories for the Reason for Noninterview Variables

The reason for noninterview coding categories depicted in Tables 2.6.4 and 2.6.5 below were constructed from the raw coding categories as shown in Table 2.6.3.  For example, the conceptual category “can’t locate” is the sum of codes “1” and “4.”  Tables 2.6.4 and 2.6.5 depict the number of respondents not interviewed by survey year, reason, and race.

Table 2.6.4  Reasons for Noninterview: 1969-2001