Building on the concept of reciprocity in directed weighted networks, we propose a framework to study legislative vote trading. We first discuss the theoretical conditions to quantify vote trading empirically. We then illustrate how our empirical framework—complementary to existing approaches—can facilitate the discovery and measurement of vote trading in roll-call data. Validation is provided via an agent-based model where the ground truth is controllable. Applications to two major studies in the field provide richer, yet consistent evidence on vote trading in U.S. politics.
