that using the Supplemental Homicide Report, which links murder data for when the crime occurred with later arrest rate data, reverses Donohue and Levitt's regression results. In 2004, Ted Joyce published a study concluding that the negative association between legalized abortion and crime rates reported in Donohue and Levitt's study was actually due to unmeasured period effects from, among other factors, changes in crack cocaine use. In 2009, Joyce reported similar, negative results after analyzing age-specific homicide and murder arrest rates in relation to the legalization of abortion across U.S. states and cohorts. In 2005 Levitt posted a rebuttal to these criticisms on the Freakonomics weblog, in which he re-ran his numbers to address the shortcomings and variables missing from the original study. The new results are nearly identical to those of the original study. Levitt posits that any reasonable use of the data available reinforces the results of the original 2001 paper. 2004 study by Donohue and Levitt In 2004 a study by Donohue and Levitt was published in University of Wisconsin Press. They address criticism from a 2003 by Joyce study that showed no negative correlation between crime and legalized abortion during the crack epidemic in the late 1980s. Donohue and Levitt show a negative still exists if the range of years examined were extended beyond those analyzed in the 2003 study, and the effects of the crack epidemic were adequately controlled. 2005 criticism by Foote and Goetz Later in 2005, Christopher Foote and Christopher Goetz claimed that a computer error in Levitt and Donohue's statistical analysis led to an artificially inflated relationship between legalized abortion and crime reduction. Once other crime-associated factors were properly controlled for, they claimed that the effect of abortion on arrests was reduced by about half. Foote and Goetz also criticize Levitt and Donohue's use of arrest totals rather than arrests per capita, which takes population size into account. Using Census Bureau population estimates, Foote and Goetz repeated the analysis using arrest rates in place of simple arrest totals, and found that the effect of abortion disappeared entirely. Donohue and Levitt subsequently published a response to the Foote and Goetz paper. The response acknowledged the mistake, but showed that with different methodology, the effect of legalized abortion on crime rates still existed. Foote and Goetz, however, soon produced a rebuttal of their own and showed that even after analyzing the data using the