Of Shirking,Outliers,and Statistical Artifacts

Abstract

It has been previously argued that there is substantial evidence that lame-duck Republican members of Congress were less supportive of the impeachment of Bill Clinton than their colleagues who returned in the 106th Congress. The author shows that this conclusion—based on a marginally significant interaction term—is actually the result of two statistical artifacts: the choice of estimator used and the inclusion in the model of five Democratic representatives who voted for some of the articles of impeachment—most notably, Paul McHale of Pennsylvania, the only lame-duck Democrat who supported impeachment. Using the ordered logit estimator (instead of ordered probit, as was previously used), estimating the model with only Republican members included, or excluding an outlier among the Democrats results in the effect becoming statistically insignificant. The long-term evidence of shirking by impeachment supporters is also very limited. On balance, the evidence suggests that retiring Republicans did not engage in shirking when making decisions on whether to vote for impeachment.