st: Mean calculation under consideration of different dates

[shausen@smail.uni-koeln.de]

Hi everybody
I consider myself as a Stata beginner and I guess that a more advanced  
user should easily solve this problem.

I've got a large dataset that includes forecasts of growth rates for  
different periods reported by different analysts at different dates. I  
already sorted the data to make sure that the analysts forecasts refer  
to the same firm and the same date.
In anext step the mean of the analysts growth rate forecasts should be  
calculated under the assumption that only those forecasts should be  
taken into account that were issued maximum 90 days prior to the  
forecast of a certain analyst.
analyst   est date    forecast   mean
11       15.Feb 2010    0,3      0,225
22       08.Jan 2010    0,2      0,3
33       01.Jan 2010    0,25
44       01.Nov 2009    0,35

The mean calculation for analyst 11 for example consists of the  
forecasts of analyst 22 and analyst 33 to be in line with the maximum  
90 days assumption.
In addition the analysts own forecast should not be considered when  
calculating the mean but I guess Stata does it automatically.
Any hints or tips are warmly welcomed.
Thanks in advanced

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