Merging data, part 2: Multiple-key merges
27 May 2011
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Multiple-key merges arise when more than one variable is required to uniquely identify the observations in your data. In Merging data, part 1, I discussed single-key merges such as
. merge 1:1 personid using ...
In that discussion, each observation in the dataset could be uniquely identified on the basis of a single variable. In panel or longitudinal datasets, there are multiple observations on each person or thing and to uniquely identify the observations, we need at least two key variables, such as Read more…