James P. Scanlan, Attorney at Law

The illustration below  is related to the illustration in the Concentration Index sub-page of the Measuring Health Disparities page.  It is intended to show that the  Gini Coefficient is not a useful measure of a disparity because, like other measures (including the Concentration Index), the Gini Coeficient is affected by the overall prevalence of an outcome.

Table 1 below is based on the data in Table 1 of the BSPS 2006 presentation.,[i] which show failure and success rates for  advantaged (AG) and disadvantaged (DG) groups at various points defined by the AG failure rate.  The table shows not only that the Gini Coefficient changes as the prevalence of an outcome changes, but that that coefficients based on the favorable and the adverse outcome change in the opposite directions. 

A versio of the this table was originally presented as Table 1 in the 2008 Comment on Boström and Rosen Scan J Pub Health 2003 .[ii]

Table 1:  Gini Coefficients for Falling Below and Above Each Point Defined by the Advantaged Group’s Failure Rate in Table 1 of BSPS 2006.