Interview Methodology

Interview Methodology

Interview Methods and Target Universe

Listings of respondents to be interviewed were generated by Census and distributed to its 12 regional offices. Current addresses and contact information were generated from information on the various Household Record Cards as well as through a postal check conducted by Census. Cases were assigned to interviewers who lived in the same geographic area as the respondent. For each respondent in their caseload, interviewers received copies of the questionnaire, respondents' Household Record Cards, flashcards, and information booklets.

Interviewers were responsible for contacting each respondent in their caseload and for using additional local resources to locate respondents who had moved since the last interview. Respondents who had moved outside the geographic district of their original interviewer were assigned another interviewer unless there was no interviewer nearby. In the latter event, an effort was made to interview the respondent by telephone.

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

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

The average length of an interview varied depending on the type conducted, with personal interviews lasting from 50-60 minutes and telephone interviews averaging 20-25 minutes. No stipends were paid to respondents in the men's cohorts for their participation in the NLS.

Respondents selected for interviewing each year were, with the exceptions noted below, those who had participated in the initial year interviews and who were alive, living within the United States at the interview date, and noninstitutionalized. Subsequent to the first year interview for each cohort, those respondents who had refused to be interviewed were dropped from the sample; respondents who had been noninterviews for reasons other than death or refusal for two consecutive years were also eliminated from attempted interviewing. This noninterview exclusion was not applied to those members of the Young Men cohort who were subsequently inducted into the Armed Forces. No interviews were attempted with this group while they were on active military duty. They were, however, retained in the sample and attempts were made to reinterview them as soon as they left active military service. Table 2 depicts reasons for exclusion from the eligible samples.

Table 2. Reasons for Exclusion from the Eligible Samples: The Original Cohorts

  Years Exclusion Reason in Effect
Out-of-Scope Reason Older Men Young Men
Institutionalized All years except the 1990 survey during which interviews were conducted with both institutionalized respondents and widows All years
In the Armed Forces All years All years
Residing outside the U.S. All years All years
Deceased All years except the 1990 survey during which information on deceased respondents was collected from interviews with 1,206 widows (or other next-of-kin) of deceased respondents and with a select number of men who had been reported deceased at an earlier survey point All years
Refusal during any one previous interview All years except 1990 All years
Dropped due to two consecutive noninterviews for reasons other than refusal, death, or membership in the Armed Forces 1968-83 1969-81 excluding Young Men enlisted in the Armed Forces
Congressional refusal1 1983 NA
1 Congressional refusal refers to a congressional representative requesting a respondent not be contacted again for an NLS survey after a respondent has completed one or more survey rounds.

Survey design and fielding procedures for the 1990 Older Men resurvey differed substantially from those employed during earlier interviews. Respondents in this cohort were last surveyed in 1983 and, if living, would have been between 69 and 83 years of age at the time of the 1990 interviews. It was expected that nearly half of the original cohort members could be deceased by the time of this resurvey.

The goal of the 1990 interviews was expanded to include obtaining information about the original cohort member regardless of his ability to respond. Questionnaires were designed for interviews with not only respondents, called "sample persons" for the purposes of this survey, but with widows of deceased sample members, or other next-of-kin in the absence of a widow. Information was to be collected not only on the labor market activities, retirement experience, and health of the respondent, whether living or deceased, but also on the widow's work experience, household composition, and family income. Institutionalized sample persons or widows--those who resided in nursing homes, homes for the needy, mental institutions, correctional facilities and long stay hospitals--were to be interviewed. Staff members at institutions could be contacted to provide information on residency within and medical insurance coverage for long-term care facilities. To assess cognitive functioning, e.g., orientation to time and place, long-term memory, and arithmetic ability, the Short Portable Mental Status Questionnaire (SPMSQ) was administered to all sample persons and widows.

Proxy interviews were encouraged in cases where the sample person was physically or mentally unable to participate. Eligible proxies, in order of preference, included a sample person's wife, child, relative, friend, or neighbor, with those residing with or close to the respondent (e.g., in the same household, in the same community) preferred over those living some distance away. Finally, Census address information, which had last been updated in 1983, was supplemented by locator information from the Social Security Administration for both sample persons and their beneficiaries. These unusual procedures resulted in some information being collected from or about 4,298 (86%) of the original cohort members. Interviews were completed with 2,092 original sample persons (90% of those designated by Census as alive in 1990) and with 2,206 respondent widows or other next-of-kin (82% of those designated deceased before the interviews began). Table 3 summarizes response rates and types of interviews for the 1990 resurvey.

Table 3. Types of Interviews by Residence Status: 1990 Older Men Resurvey

  Residence Status
Types of Interview Total Noninstitutionalized Institutionalized Unknown
Sample Person or Proxy 2092 1954 60 78
Sample Person 1899 1877 22 --
Proxy for Sample Person 151 77 33 41
Staff Member for Sample Person 5 -- 5 --
Sample Person & Proxy 37 -- -- 37
Widow or Widow Proxy 1341 1205 38 98
Widow 1213 1201 12 --
Proxy for Widow 112 4 24 84
Staff Member for Widow 2 -- 2 --
Widow & Proxy 14 -- -- 14
Other Next-of-Kin 865 865 -- --
Total Interviews 4298 4024 98 176