Comparing Campaign Finance and Vote-Based Measures of Ideology

I show that campaign finance-based measures of ideology (CFScores) and vote-based measures of ideology (NOMINATE) have become entirely uncorrelated among Democratic legislators in the US Congress. This is not the case for Republican members of Congress or for state legislators of either party. I show this by comparing Bonica’s CFScores with NOMINATE scores from 1980 to 2018 and with state legislator ideology scores (NPAT) from 1996 to 2012. The decline in correlation begins in the early 2000s and approaches zero in 2014, where it has remained since 2014. These previously undocumented results illustrate a dramatic change among Democrats in Congress in the relationship between fund-raising and voting—two activities that consume a significant portion of legislators’ time and attention. Furthermore, scholars of representation need to be aware that different latent measures of ideology can lead to different conclusions about the relationship between legislators and their constituents.