NBER Working Papers by Robert J. LaLonde

Using data from a social experiment, we estimate the impact of training on the duration of employment and unemployment spells for AFDC recipients. Although an experimental design eliminates the need to construct a comparison group for this analysis, simple comparisons between the average durations or the transition rates of treatments' and controls' employment and unemployment spells lead to biased estimates of the effects of training. We present and implement several econometric approaches that demonstrate the importance of and correct for these biases. For the training program studied in the paper, we find that it raised employment rates because employment durations increased. In contrast, training did not lead to shorter unemployment spells.

This paper reassesses the evidence on the assimilation and the changing labor market skills of immigrants to the United States. We find strong evidence of labor market assimilation for most immigrant groups. For Asian and Mexican immigrants the first ten years experience in the united States raise earnings by more than 20 percent. Further, this estimate may understate the actual rate of assimilation because of the sharp decline in the relative wages of unskilled U.S. workers. We also find little evidence of declining immigrant "quality" within ethnic groups. The diminished labor market skills of new immigrants result entirely from changes in the immigrants' countries of origin.