Table 2.

Example 2: Illustration of Differences in Weighted and Nonweighted Disparity Measures, Based on Reported Gonorrhea Rates From 2007 (Scenario C) and 2010 (Scenario D)

		Scenario C (2007)		Scenario D (2010)
Racial/Ethnic Group	Population	No. Cases	Rate (per 100,000)	No. Cases	Rate (per 100,000)
White, non-Hispanic	200,000,000	54,000	27.0	46,800	23.4
Black, non-Hispanic	40,000,000	206,080	515.2	170,480	426.2
Hispanic	55,000,000	29,100	52.9	26,350	47.9
A/PI	20,000,000	2,900	14.5	2,880	14.4
AI/AN	3,000,000	2,485	82.8	3,222	107.4
Overall	318,000,000	294,565	92.6	249,732	78.5
Disparity Measure
Index of Disparity		133.0		134.1
Weighted Index of Disparity		114.8		112.1
Gini coefficient		0.619		0.608

In this example, the unweighted measure (Index of Disparity) indicates an increase in disparity from 2007 to 2010, whereas the weighted version of the measure (Weighted Index of Disparity) indicates a decrease in disparity. The Gini coefficient, which like the Weighted Index of Disparity accounts for population size of the racial/ethnic groups, also indicates a decrease in disparity from 2007 to 2010.

The rates in scenarios C and D correspond to reported gonorrhea rates in 2007 and 2010, respectively.²⁵ For ease of display and comparison, the populations used in all examples reflect rounded approximations of 2014 estimates. Because we did not use actual population estimates for any given year, the case numbers were adjusted manually to correspond to the reported rates for the given year, and therefore do not match the case numbers in the surveillance reports. Similarly, the overall rate was calculated from the adjusted number of cases for each subgroup and therefore does not match the overall rate in the surveillance reports.