External validity is the extent to which we can generalize the findings of a study to other situations, people, settings, and measures.External validity can be increased by using broad inclusion criteria that result in a study population that more closely resembles real-life patients, and, in the case of clinical trials, by choosing interventions that are feasible to apply.
Researchers often attempt to assess external validity by comparing data from an experiment to external data.
How to examine external validity within an experiment - Kowalski - Journal of Economics & Management Strategy - Wiley Online Library
Dekkers (2010) has this very nice paper on external validity in IJE: Article How to assess the external validity of therapeutic trials: A...
- it gives you a good overview on the (qualitative) aspects of external validity of clinical trials.If you want to "measure" the changes of treatment effect when applying trial results into another population, you might want to look at "transportability", a new rising topic in causal inference. See Westreich (2017, AJE) for a brief introduction: Article Transportability of Trial Results Using Inverse Odds of Samp...
and Inoue (2022):Article Generalizability and Transportability of the National Lung S...
for an example of applying transportability.- Badges
- Science method