Measuring disability with parsimony.

PRIMARY OBJECTIVE: Health surveys, especially those for older persons, include numerous detailed items about disability. There has been little effort to develop a global disability item, that is, one question that covers the concept of disability briefly but well. This article discusses how parsimony can be achieved through a single item, or less desirably by reductions of detailed items.

MAIN OUTCOME AND RESULTS: Results of three analyses on the issue of compact disability indicators, using public-use data sets (AHEAD, HRS, BRFSS), are presented. The analyses study relationships of global disability to both detailed disability items and global health. Overall, the results show that a global disability item has good coverage of specific disabilities and is distinct from self-rated health.

CONCLUSIONS: Routine inclusion of a global disability item in surveys is recommended, and specific suggestions are made to aid its design.