Methodological issues in measuring health disparities.

OBJECTIVES: This report discusses six issues that affect the measurement of disparities in health between groups in a population: Selecting a reference point from which to measure disparity. Measuring disparity in absolute or in relative terms. Measuring in terms of favorable or adverse events. Measuring in pair-wise or in summary fashion. Choosing whether to weight groups according to group size. Deciding whether to consider any inherent ordering of the groups. These issues represent choices that are made when disparities are measured.

METHODS: Examples are used to highlight how these choices affect specific measures of disparity.

RESULTS: These choices can affect the size and direction of disparities measured at a point in time and conclusions about the size and direction of changes in disparity over time. Eleven guidelines for measuring disparities are presented.

CONCLUSIONS: Choices concerning the measurement of disparity should be made deliberately, recognizing that each choice will affect the results. When results are presented, the choices on which the measurements are based should be described clearly and justified appropriately.