Gender bias and selection bias in House elections

We demonstrate that female incumbents are of higher average candidate quality than male incumbents. This quality difference is the result of barriers to entry faced by potential female candidates, although the observed effects of this quality differential on vote share are partially masked by the fact that female incumbents are also more likely to be opposed or to be opposed by high quality challengers. Using data from House elections for 1984-1992, we estimate that the gender-based differential in candidate quality yields an extra six percentage points of vote share for female incumbents.