Merging And Appending Data With Stata

Introduction

merge-ing data and append-ing data are often confused. In this post, I try to quickly distinguish the two.

merge-ing Data Compared To append-ing Data

1. Visually, merge can be thought of as placing data sets side by side, effectively making a wider data set.
2. Visually, append can be thought of as stacking data sets on top of each other, making a longer data set.
3. In both procedures, you likely want to start by use-ing each data set, only keep-ing variables of interest, and save-ing under a new filename.
4. In merge-ing you are more likely to want to ensure that variables in different waves will have different names. You may have to rename variables to accomplish this.
5. When append-ing, you are more likely to want rename the variables in different waves of data so that they have the same name. Make sure each wave of data has a time variable for the wave before you append!

merge-ing data

append-ing data