In order for the code used to create this data frame to work text files available on Dehejia's webpage http://www.nber.org/~rdehejia/data/nswdata2.html need to be downloaded and stored in the working directory. The data frame consists of 297 treated units from a randomized evaluation of a labor training program, the National Supported Work (NSW) Demonstration, and 314 nonexperimental comparison units drawn from survey datasets.