Cliff Carubba and Juan Estrada (Emory) will be presenting their working paper, "Estimating Network Effects and Their Impact on Congressional Polarization," on Monday, September 11, in the Method's Workshop. The talk will go from 2:30-4pm in Room 217.
Abstract: This paper presents a novel approach to identifying and estimating the parameters of a model where legislators choose their revealed political ideology based on their roll-call votes. We investigate the influence of peers' behavior on legislators' optimal ideology choices within the U.S. Congress by considering diverse professional connections, including cosponsorship, committee membership, and same-state links. To address the challenge of identifying heterogeneous network effects, we propose an original strategy that leverages our theoretical model's statistical implications, enabling us to uncover a credible source of exogenous variation. In equilibrium, interest groups' contributions to state and federal legislators are correlated, and the direct contributions influence federal politicians' revealed ideology. Crucially, we find that the variation in state contributions is uncorrelated with federal legislators' private ideologies for those who are distantly connected in the network space. We employ a Generalized Method of Moments estimator that incorporates the identifying assumptions, delivering consistent and asymptotically normal estimators for our parameters of interest. Through the empirical analysis, we validate our main identifying assumptions and observe strong peer effects within the cosponsorship network and a direct influence of interest groups contributions on legislators' revealed policy positions. Substantively, we argue that the polarizing impact of money in politics, alongside the echo chamber dynamics resulting from partisan connections and social multipliers, provides a plausible and coherent explanation for the observed increase in polarization.