A COMPARATIVE-ANALYSIS OF ADL QUESTIONS IN SURVEYS OF OLDER-PEOPLE

This article describes questions designed to assess limitations with r espect to activities of daily living (ADLs) that were asked on the fir st wave of the AHEAD study, and it assesses their cross-sectional meas urement properties. It also provides comparisons between those questio ns and parallel questions that have been asked on two other surveys of the elderly population in the United States: the 1984 Supplement on A ging (SOA) to the National Health Interview Survey and the screener fo r the 1982 National Long Term Care Survey (NLTCS). It also compares a single item from the 1990 Census. It then compares the ways in which t he same individuals answer these different versions of ADL questions, using data from subsamples of the AHEAD respondents who were also aske d the SOA, NLTCS, or Census questions. The analysis shows that there i s a substantial amount of measurement error in the answers to ADL ques tions, and it suggests that this is a major contributor to apparent im provements and declines in functional health observed in longitudinal data.