Friends in High Places
研究发现美国政客间的校友关系显著影响参议院投票行为，其效应接近州级因素的60%，并用于投票交易和争取专项拨款。
We demonstrate that personal connections amongst US politicians have a significant impact on Senate voting behavior. Networks based on alumni connections between politicians are consistent predictors of voting behavior. We estimate sharp measures that control for common characteristics of the network, as well as heterogeneous impacts of a common network characteristic across votes. We find that the effect of alumni networks is close to 60 percent as large as the effect of state-level considerations. We show that politicians use school ties as a mechanism to engage in vote trading (“logrolling”), and that alumni networks help facilitate the procurement of discretionary earmarks.