Tuesday, March 14, 2006

st: Updating master dataset with a transation dataset

Hi, I am relatively new to Stata, although I have programming experience in SAS and C. This is what I would like to do, but I cannot figure out how to do it in Stata:

1. My master dataset has hundreds of variables, two of which, var1 and var2 I combine to use as a unique identifier of each record.

2. My second dataset, the transaction dataset, has 4 variables: two of them are the same two as in the master dataset, var1 and var2. They are not unique identifiers on this dataset. a. The third variable in the transaction dataset, (var3), contains the name of a variable in the master dataset which is to be updated. This variable name is different from record to record on the transaction dataset. b. The fourth variable, var4, contains the data that is to update var3 on the master dataset.

Ex: I would match record from transaction dataset with master dataset record on var1 and var2. Then I would look at the contents of the var3 on the transaction dataset which would tell me the name of the variable that needed to updated on the master dataset. Var4 on the transaction dataset would tell me what the contents of this updated variable is to be.

It is possible to have several records in the transaction dataset all with the same unique identifier, instructing the system to update different variables on the same record of the master dataset.

Now I know that I can just create a series of replace varname with the contents of var4 statements and copy and paste this data into a do-file, and run it that way.

But that is not very efficient, and I need to do this over and over again, so if there is a way I could read the transaction dataset, then retrieve the appropriate record from the master dataset, update the specified variable with it's contents from var4, that would be better. Is there anyway I can do this in Stata? Thank you so much for your help. Alice

Alice Muehlhof Research Assistant Woodrow Wilson School Princeton University

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