st: Calculating rolling averages

[William Hauser <whauseriii@gmail.com>]

Hi all,
I am attempting to calculate the percentage of cases handled by a
judge that meet some criterion (e.g. being a violent offender).  The
data cover 13 years so obviously the averages for each judge change
overtime.  My first thought was the following command:

bysort id date:  egen pct=mean(offense_9) if date[_n]>date

I had hoped that Stata would calculate the average based only on cases
with a earlier (smaller) date but instead the command results in all
missing values because date[1]<date[2] and so forth.

Another thought was to use the rolling command (which I'm not sure how
to do anyways) but this requires the use of tsset.  When I tsset my
data I get an error, "repeated time values within panel" presumably
because each judge handles multiple cases a day.

I imagine this is probably a simple matter of syntax but I am in well
over my head.  Any insight you could provide would be greatly
appreciated.

Will Hauser

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