The supplemental.zip archive for this publication contain two files:   
1. meta-information.pdf 
2. cohort_migration.do 
 
1. meta-information.pdf 
This file provides information about where to obtain each dataset and under what conditions (license). It also indicates sample sizes and describes the variables used in the analysis.

2. cohort_migration.do 
This is a STATA do file created in version 13. The file contains the authors? data manipulation and analysis code to run the analysis for each dataset.