Forecasting the partisan composition of the house as a function of seniority

This note examines the influence of seniority of the partisan composition of the House of Representatives. A model is developed to compute the re-election probabilities as a function of the levels of seniority. These estimates, together with the composition of the immediately preceding congress, are then used to estimate the composition of any congress and the results compared to the actual electoral outcomes. The end result is a partisan composition or the House independent of the short-term fluctuations created by issues relevant to the individual elections. In addition, measures of accuracy of the estimates are computed in order to assertain how much of the variation in the data is left to be explained by issue-oriented factors.