I am trying to calculate the EGI (Ellison and Glaeser's index of geographical concentration) using the STATA module developed by Jay Dev Dubey. I have a query regarding the formula used. The help file on the module states the following:


Ellision and Glaeser's index

EGIi = (GIi - HIi)/(1-HIi)

where, GIi = Sum of squared deivation of ith industry's state employment share from
a measure Ss.

Ss = employment share ith state in the average industry.

Hi = Herfindhal style measure of the plant level concentration of employment in ith
industry.

EGI syntax return and store the Ellision and Glaeser's index for each industry variety
as a new variable. By choosing suitable index option it may also return other components.
Option


However, the 1997 paper has the following formula,

Array

From what I am understanding, the EGI module on STATA is missing the following.

Array

Just wanted to check if my understanding is correct here, or whether the EGI STATA module is correct.

Thanks!