Bribery or just desserts?

"Evidence on the relationship between political contributions and legislators' voting behavior is marred by concerns about endogeneity in the estimation process. Using a legislator's offspring sex mix as an exogenous variable, we employ a two-stage least squares estimation procedure to predict the effect of voting behavior on political contributions. Following previous research, we find that a legislator's proportion daughters has a significant effect on voting behavior for women's issues, as measured by score in the "Congressional Record on Choice" issued by NARAL Pro-Choice America. In the second stage, we make a unique contribution by demonstrating a significant impact of exogenous voting behavior on PAC contributions, lending credibility to the hypothesis that Political Action Committees respond to legislators' voting patterns by "rewarding" political candidates that vote in line with the positions of the PAC, rather than affecting or "bribing" those same votes -- at least in this high profile policy domain"--National Bureau of Economic Research web site.