st: referencing values of others on a variable

[Viktor Emonds <Viktor.Emonds@soc.kuleuven.be>]

Hello,

I have a file where for each student, there are as many observations as there are possible ties to other classmates (directed, based on nomination), with the following basic structure:

id student  id alter     tie

001               002      1      
001               003      0
001               004      0
001               005      1
002              001        0
002             003         0
002              004       0
002              005       1

I would like to compute indices of friendship segregation along ethnic lines and need to evaluate whether the ethnicities of ego and alter match or not. How to do so in Stata syntax?

I know you can refer to values on a variable for another observation, e.g. samevalue= var==var[_n-1], but I cannot seem to extend this to something like samerace= race==race[idstudent=idalter]. Any ideas on how I can do this? Thanks!

Best,

Viktor 
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