Vetoes, bargaining, and boundary conditions

"Testing Theories of Congressional-Presidential Interaction with Veto Override Rates" (henceforth "Veto Override Rates") offers several tests of two models of vetoes and finds the models wanting. The paper concludes that something is seriously amiss with the models. In my view, the problem lies not in the models but in the tests. Understanding why the tests miss the mark is helpful in understanding models of veto politics, and more generally in thinking about testing strategies when multiple models analyze different causal mechanisms that hold under different circumstances. I should note immediately that the effort in the paper to think hard about override rates is admirable; it simply does not go far enough.