Experts' political preferences and their impact on ideological bias: an unfolding analysis based on a Benoit-Laver expert survey

Expert surveys have become increasingly popular among political scientists. One of the problems of using surveys (of any sort) to estimate party positions is that respondents can be influenced by their subjective political views. As a consequence, experts may give biased responses, and such (ideological) bias may affect certain parties more than others. In this paper, we use the latest expert survey of Benoit and Laver (2006) to unfold the ideal points of the respondents to the survey. By employing the estimated ideal points, we show that in almost 16 percent of the cases analyzed, there is evidence of an ideological bias in the experts' placements of parties along the left-right dimension, especially among right-wing parties (but not necessarily extreme-right parties). We examine two methods designed to generate less biased estimates. The first one is directly based on a regression technique, while the second is based on the negligibility of ideological bias in experts' answers to more specific policy questions. The paper concludes by examining the consequences of these findings for empirical research.