Locating Longitudinal Respondents After a 50-Year Hiatus

Many longitudinal and follow-up studies face a common challenge: locating study participants. This study examines the extent to which a geographically dispersed subsample of participants can be relocated after 37 to 51 years of noncontact. Relying mostly on commercially available databases and administrative records, the 2011-12 Project Talent Follow-up Pilot Study (PTPS12) located nearly 85 percent of the original sample members, many of whom had not participated in the study since 1960. This study uses data collected in the base year to examine which subpopulations were the hardest to find after this extended hiatus. The results indicate that females were located at significantly lower rates than males. As expected, sample members with lower cognitive abilities were among the hardest-to-reach subpopulations. We next evaluate the extent to which biases introduced during the tracking phase can be minimized by using the multivariate chi-square automatic interaction detection (CHAID) technique to calculate tracking loss adjustments. Unlike a 1995 study that found that these adjustments reduced statistical biases among its sample of located females, our results suggest that statistical adjustments were not as effective in PTPS12, where many participants had not been contacted in nearly 50 years and the tracking rates varied so greatly across subgroups.