Although the studies differ in population coverage, sample design, method and periodicity of measurement, use of proxies, and treatment of nonresponse and missing data, the authors conclude that most analyses using data from the post- 1980 period show declines in the percentage with moderate disability and IADL disability. These declines have been shown to vary by gender (18, 47) and level of education (18); and they also differ between the young-old and the old-old (19). Generally, there is more improvement in less-severe disability
