Are Donation-Based Measures of Ideology Valid Predictors of Individual-Level Policy Preferences?

Abstract

This paper validates donation-based measures of ideology against a rich battery of policy items from the Congressional Campaign Election Study (CCES). Donation-based measures are powerful predictors of policy preferences for a wide range of issues and successfully discriminate between donors from the same party. The overall predictive accuracy and relative improvement over party are comparable to what is achieved by scaling roll call votes in legislatures. The results add to an existing body of evidence on the internal validity and reliability of donation-based measures. They also resolve a standing debate in the literature over whether political donations are a valid indicator of donors’ policy preferences.

Keywords: Preference Measurement, Ideology, Ideal Point Estimation, CCES, Donors, Campaign Contributors, Validation, Predictive Validity