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st: generating variables conditional on others (again..)


From   Linn Renée Naper <linn.naper@ecgroup.no>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   st: generating variables conditional on others (again..)
Date   Thu, 30 Apr 2009 15:26:27 +0200

I would like to do something like this:

forvalue m=1/12 {
replace X3 = X2 in [X1==`m' + 1]
}

This is not possible, but I think it illustrates my problem as I need to tell stata to replace a variable (X3) with values (X2) from other observations identified by a third variable (X1).

I have a sample with a date-identifier, variable X1 giving the current month and a variable X2 giving the mean price level for the same month. Thus, within the same month the variable is constant. Data have several years.

Now I need a variable X3 which gives me the mean price level (X2) for the coming month (actually I will generate several variable for the price level for all months to come, but I guess the logic will be the same here). 

Thus, I need to generate a variable X3 (g X3=.) and then replace it with the values from X2 given in other observations. For month 1 (X1=1, January) X3 should contain the values of X2 when X1==2 (February) and so on. 

I know I posted a similar problem I while ago, but the structure of the data here is not the same, so I'm stuck again :(

Linn

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