To celebrate the 40th anniversary of the paper The Central Role of the Propensity Score in Observational Studies for Causal Effects published in Biometrika in 1983, the journal Observational Studies had a special issue highlighting the methods in the paper and developed since. This led us to take a closer look at this seminal paper, and in doing so we noticed mention of a visual diagnostic tool that we haven’t see used often but might be useful for exploring potential treatment effect heter...
