Abstract
<p>"Hilbert problems" are a great idea to galvanise research in the scientific study of religion, yet how do we go about answering these – or any other scientific questions of interest – empirically? This "meta-scientific" methodological aspect of research was largely missing from the original Hilbert problems and the 10 year follow-ups. Here, I want to focus on the importance of a clear and unambiguous estimand – the target quantity a study wants to estimate – and how this shapes all aspects of research, from synthesising existing research, data collection, statistical analysis and interpretation of results. At present, this is often vague or left unspecified, yet making progress on these Hilbert problems requires that researchers can clearly and unambiguously answer the question: "What is your estimand?"</p>