Space we’ll only show the output for one of the datasets. We would want to do this for all three of our datasets, but to save WeĪlso note that the variables we want from this dataset are in fact in theĭataset. (the data must be sorted by the id variable or variables in order to merge). Shows is that the variable id is numeric, and that the data are unsorted Lot of useful information, for our purposes the most important things it Opening file (this can be handy if the files are very large), all we have to do is A simple exampleĪ good first step is to describe our data. The id variable(s) are, you can begin to merge the datasets. Once you have identified all the variables you need, and know what Variables (the specific storage type is not important, as long as they are Must also be a string in all other datasets, and the same is true of numeric Additionally, if the variable is a string in one dataset, it In order for Stata to merge the datasets, the id variable, or variables, will have to have the same nameĪcross all files. Subject id and date or wave are often needed to uniquely identify an
Two or more variables are needed, this is commonly seen in panel data where ForĬross sectional data, this will typically be a single variable, in other cases, This willĪllow you to match the data from different datasets to the right person. An id variable is a variable that is unique to a case (observation) in the dataset.įor a given individual, the id should be the same across all datasets. The variables you want for your analysis, you need to know the name of the id Merge the segments into a new file that contains all of the variables you intendįirst, you’ll need to figure out which variables you need, and which datasetsĬontain them, you can do this by consulting the codebook. Work with information contained in two or more data files it is necessary to Variables you want to use will often be scattered across several datasets. Whenĭata is distributed in multiple files, the It is not uncommon for data, especially survey data, to come in multipleĭatasets (there are practical reasons for distributing datasets this way). Grateful for their permission to reproduce this FAQ here. This FAQ is was based on a page developed by the Graduate Statistical Assistant However, the old syntax displayed on this page will still work in newer versions of Stata.
The current version of merge uses a different syntax (requiring a 1:1, m:1, or 1:m specification) and does not allow more than one file to be merged in a single merge command. NOTE: This page describes usage of an older version of the merge command (prior to Stata 11), which allowed multiple files to be merged in the same merge command.
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