The Impact of Legalized Abortion on Crime: Comment
Revised article published in the Quarterly Journal of Economics vol. 123, no. 1 (February 2008): 407-423.
This comment makes three observations about Donohue and Levitt's  paper on abortion and crime. First, there is a coding mistake in the concluding regressions, which identify abortion's effect on crime by comparing the experiences of different age cohorts within the same state and year. Second, correcting this error and using a more appropriate per capita specification for the crime variable generates much weaker results. Third, earlier tests in the paper, which exploit cross-state rather than within-state variation, are not robust to allowing differential state trends based on statewide crime rates that pre-date the period when abortion could have had a causal effect on crime.
This paper was originally published as "Testing Economic Hypotheses with State-Level Data: A Comment on Donohue and Levitt (2001)" and was revised in January 2008.