This report describes the results of an experiment conducted as part of Round 16 of the National Longitudinal Survey of Youth (NLSY). The NLSY was originally fielded in 1979; the sample consists of persons who were 14 to 21 years old at that time. Through the first 15 rounds of data collection, interviews were conducted every year and the questions generally covered the period since the last interview. The questions concern a range of topics, including labor force and educational experiences, health and disability, marital status, income, and program participation. With Round 17, the schedule of data collection changes. From that round on, interviews will be done every other year; this change will double the length of the period covered by many of the questions. The Round 16 experiment tested the effects of this change in the data collection schedule.
For Round 16, 900 NLSY sample members randomly assigned to be interviewed about the period since their Round 14 interview, which was conducted about two years earlier. Their responses were compared to a group of approximately 8,000 cases who were assigned to be interviewed about the one-year period since their Round 15 interview. Both groups were restricted to NLSY sample members who had completed both the Round 14 and Round 15 interviews and both got the same questionnaires (except for the differences in the length of the period covered by the interview).
The analysis examined several labor force and recipiency variables — the number of jobs the respondents reported, the number of gaps between jobs, and whether they reported receiving unemployment, Food Stamps, or AFDC payments. The two-year recall period had little discernible effect on means and proportions for the sample as a whole. There was some decrease in the number of jobs respondents reported for the most recent year, but none of the other analyses showed much overall impact of the two-year recall period.
However, a closer examination of the results found substantial errors in the reports covering the two-year period. The two-year period covered by the Round 16 interviews included the one-year period the respondent had already reported about in Round 15. The Round 16 reports sometimes failed to reproduce the information the respondent had provided in the earlier interview. The discrepancies in reports concerning this overlapping period were especially marked among respondents who had the complicated job and recipiency histories. On the average, such respondents reported fewer jobs and less recipiency in their Round 16 interview than they had in Round 15. The limited overall impact of the two-year recall period thus appears to reflect the stable circumstances of most of the respondents. It is easy for respondents to remember their jobs if they have not changed jobs in many years; it is far more difficult for them to remember their jobs if they change jobs frequently. Among the subgroup of respondents with dynamic job or recipiency histories, the longer recall period had a marked impact on reporting.