Generalizing survey experiments using topic sampling: an application to party cues

Abstract

Scholars have made considerable strides in evaluating and improving the external validity of experimental research. However, little attention has been paid to a crucial aspect of external validity – the topic of study. Researchers frequently develop a general theory and hypotheses (e.g., about policy attitudes), then conduct a study on a specific topic (e.g., environmental attitudes). Yet, the results may vary depending on the topic chosen. In this paper, we develop the idea of topic sampling – rather than studying a single topic, we randomly sample many topics from a defined population. As an application, we combine topic sampling with a classic survey experiment design on partisan cues. Using a hierarchical model, we efficiently estimate the effect of partisan cues for each policy, showing that the size of the effect varies considerably, and predictably, across policies. We conclude with advice on implementing our approach and using it to improve theory testing.