The purpose of this study is to
examine longitudinal data over 6 years from a national probability sample of older Americans
to obtain a mathematical picture of physical functioning as people age. We use the order of
incident disabilities to assess a hierarchy of dependency onset. The median age of incident
disability and patterns in which disabilities occur over time within individuals are evaluated to
identify the most frequent ordering of dependency across activities of daily living. This sequence
is the basis for a model that uses a profile of impairment in activities of daily living to predict
future disability in remaining activities. We also examine gender differences in the incidence of
disabilities.