Interview Methodology

National Longitudinal Survey of Older and Young Men

Interview Methodology


Interview Schedule & Fielding Periods

In the initial survey plan, respondents from each of the four Original Cohorts were to be interviewed yearly over a five-year period. 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. Due to their greater mobility, the younger groups were to continue to be interviewed annually. Because of the usefulness of these data and the relatively small sample attrition, a decision was made at the end of the first five-year period to continue the interviews for another five years. At this point, the interviewing pattern changed from a yearly 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 1981 for the Young Men and 1983 for the Older Men, when interviewing of both cohorts ceased. The Older Men or their proxies were then personally reinterviewed in 1990. Table 1 depicts the years in which each cohort was surveyed, the type of interview used, the fielding period, and the number and percent of respondents with completed interviews.

Table 1. Sample Sizes, Retention Rates, and Fielding Periods

Survey Year Type of Interview Fielding Period Total Interviewed Retention Ratea Retention Rate among
Living Respondents
Older Men
1966 Personal May - July 5020 100.0 100.0
1967 Personal May - July 4744 94.5 95.6
1968 Mail May - July 4648 92.6 95.1
1969 Personal July - Sept. 4381 87.3 91.5
1971 Personal July - Sept. 4175 83.2 90.3
1973 Telephone July - Sept. 3951 78.7 88.7
1975 Telephone July - Sept. 3732 74.3 87.2
1976 Personal July - Sept. 3487 69.5 83.4
1978 Telephone July - Sept. 3219 64.1 80.2
1980 Telephone July - Sept. 3001 59.8 78.7
1981 Personal July - Sept. 2832 56.4 76.3
1983 Telephone July - Sept. 2633 52.5 74.8
1990 Personal Oct. - Dec. 2092b 41.5 89.9
Young Men
1966 Personal Oct. - Dec. 5225 100.0 100.0
1967 Personal Oct. - Dec. 4790 91.7 91.9
1968 Personal Oct. - Dec. 4318 82.6 83.0
1969 Personal Oct. - Dec. 4033 77.2 77.7
1970 Personal Oct. - Dec. 3993 76.4 77.1
1971 Personal Oct. - Dec. 3987 76.3 77.2
1973 Telephone Oct. - Dec. 4014 76.8 78.0
1975 Telephone Oct. - Dec. 3977 76.1 77.4
1976 Personal Oct. - Dec. 3695 70.7 72.0
1978 Telephone Oct. - Dec. 3538 67.7 69.3
1980 Telephone Oct. - Dec. 3438 65.8 67.5
1981 Personal Oct. - Dec. 3398 65.0 66.8
a Retention rate is defined as the percent of base year respondents who were interviewed in any given survey year. Included in the calculations are deceased and institutionalized respondents as well as those serving in the military.
b Interviews were completed during 1990 with 2,092 surviving members of the original sample and with 1,341 widows and 865 next-of-kin of deceased respondents from whom data about the decedent was obtained. Table 3 below presents additional information on the 1990 universes.


User Notes

Although each of the personal interviews contains data of roughly the same degree of completeness, data gathered during the telephone interviews was 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 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 year since last interview. Income data, for example, were often collected for the calendar year, corresponding to the time frame for a respondent's tax records; employment data were usually collected for the year since the last interview.