The Impact of Legalized Abortion on Crime: Comment
对Donohue和Levitt关于堕胎与犯罪关系的论文提出三点评论：发现其结论性回归中存在编码错误，修正后结果变弱；且早期基于州际差异的检验在考虑州级犯罪率趋势后不稳健。
This comment makes three observations about Donohue and Levitt's paper on abortion and crime (Quarterly Journal of Economics 119(1) (2001), 249–275). 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 for differential state trends based on statewide crime rates that predate the period when abortion could have had a causal effect on crime.