Of Shirking, Outliers, and Statistical Artifacts: Lame-Duck Legislators and Support for Impeachment

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. I show 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. There can be no question that the issue of whether President Clinton ought to be impeached for alleged perjury, obstruction of justice, and abuse of power was among the most salient issues of recent congressional history. Over time became clear that there had been, at least, an intensive effort by the president to keep the truth about his relationship with a former intern a secret from the plaintiff in a sexual harassment lawsuit against him. Democratic members of Congress, particularly those in marginal districts, were widely characterized in the media as “running scared” at the prospect of the November 1998 congressional elections becoming a referendum on the president’s legal problems. While in retrospect the issue does not appear to have affected the outcome of many congressional races,1 there was certainly a perception at the time of the votes regarding the impeachment inquiry, particularly among Democrats who perceived that they faced difficult challengers in the upcoming election and that the president’s legal problems could easily become political problems of their own. The relatively poor Republican showing in the subsequent election—the result of the first midterm gain by an incumbent president’s party in living memory—led to similar speculation about the eventual fate of Republican members who supported impeachment in marginal districts. Rothenberg and Sanders (2000a) previously examined the voting behavior of representatives on impeachment, and concluded that there was evidence that retiring Republican legislators engaged in shirking—in other words, that the weakening of the ties between representatives and the electorate led retiring legislators to vote more inconsistently with constituency preferences than those who remained in Congress. Evidence of shirking in the contemporary Congress has been relatively hard to come by; hence, this result is of great interest to scholars who believe that it does take place. However, the evidence supporting this finding appears to be flawed in a number of ways. First and foremost, the choice of estimator used has a substantial impact on the statistical significance of the results—in other words, the finding is not robust across the set of appropriate estimators for their statistical model. It also appears that their finding of shirking among Republicans 1However, Abramowitz (2001) argues the scandal did affect the aggregate outcome of the 1998 House elections.