A Practical Guide to Dealing with Attrition in Political Science Experiments

Abstract Despite admonitions to address attrition in experiments – missingness on Y – alongside best practices designed to encourage transparency, most political science researchers all but ignore it. A quantitative literature search of this journal – where we would expect to find the most conscientious reporting of attrition – shows low rates of discussion of the issue. We suspect that there is confusion on the link between when attrition occurs and the type of validity it threatens when present, and limited connection to and guidance on which estimands are threatened by different attrition patterns. This is all exacerbated by limited tools to identify, investigate, and report patterns attrition. We offer the R package – attritevis – to visualize attrition over time, by intervention, and include a step-by-step guide to identifying and addressing attrition that balances post hoc analytical tools with guidance for revising designs to ameliorate problematic attrition.