“…One aspect is predictive, as illustrated by the literature that attempts to link crime to unemployment. A second aspect focuses on policy evaluation: prominent current controversies involving the use of aggregate regressions include the deterrent effect of shall-issue concealed weapons legislation (Lott and Mustard, 1997;Lott, 1998;Black and Nagin, 1998;Ayers and Donohue, 2003;Plassmann and Whitley, 2003), the deterrent effect of capital punishment (Dezhbakhsh and Rubin, 2007;Dezhbakhsh et al, 2003;Donohue and Wolfers, 2005;Katz et al, 2001;Gittings, 2001, 2006) and perhaps most controversially, the effects of liberalized abortion laws on crime (Donohue and Levitt, 2001Foote and Goetz, 2008;Joyce, 2004;Lott and Whitley, 2007).…”