What Makes Experts Reliable?

Many datasets use experts to code latent quantities of interest. However, scholars have not explored either the factors affecting expert reliability or the degree to which these factors influence estimates of latent concepts. Here we systematically analyze potential correlates of expert reliability using six randomly selected variables from a cross-national panel dataset, V-Dem v8. The V-Dem project includes a diverse group of over 3,000 experts and uses an IRT model to incorporate variation in both expert reliability and scale perception into its data aggregation process. In the process, the IRT model produces an estimate of expert reliability, which affects the relative contribution of an expert to the model. We examine a variety of factors that could correlate with reliability, and find little evidence of theoretically-untenable bias due to expert characteristics. On the other hand, there is evidence that attentive and condent experts who have a basic contextual knowledge of the concept of democracy are more reliable.