Abstract

Despite its crucial role, sample representativeness remains a controversial topic in medical science methodology. There is an ongoing debate not only about how best to define and ensure the representativeness of a sample (e.g., Rudolph et al., 2023; Porta, 2016), but also about whether representativeness is worth pursuing at all (e.g., Rothman et al., 2013). We present a new definition of representativeness in terms of causal models and argue that it is more precise and more useful than existing alternatives. We use examples to demonstrate the types of evidence that can support assumptions of representativeness.