How do I calculate the index of disparity

[jkwarteng]

How do I calculate the Index of disparity with SAS? 

IDisp=∑(|yj – yref|/J - 1)/yref X 100

yj indicates the measure of health status in the jth
group, and yref is the health status indicator in the reference
population. J is the total number of groups.

[ballardw]

First you may want to double check your spelling. You have a single | and I'm not sure if you intended to have | yj -yref | or | yj - yrefj | or something else. Also where you use E is that supposed to be the Expectation or something else.

[mkeintz]

And what  is "yref"? Is it calcuated from the Yj sample?

If yref is mean of y,  then you are simply asking for 100 times the mean absolute deviation, scaled by the mean.