st: xtile from the start of a period

[John Hund <jhund@tulane.edu>]

Hey all--

A simple question whose answer I can't find in the very interesting  
xtile by groups discussion.  In this case I have data (market values)  
on companies (compid) monthly. Ideally I would like to generate a  
variable containing the decile rank of the company based on their  
market value at the beginning of a period (i.e. their decile in  
January 1970) and have that variable contain the decile rank for all  
monthly observations of the compid for a particular time window (i.e.  
1970-1975). That is, there would be a variable that contains the  
decile rank from Jan70 for all monthly observations of a compid for  
the next 5 years.  I suspect that my question is less about xtile and  
more about filling in, since it is easy to get the decile rank for  
the first month...I just can't "fill" it in for the next (in this  
case) 59 observations of each company.

Thanks for your help,
John

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