Evidence-appraisal glossary
Temporal Validation
Temporal validation checks a prediction model on patients from a later time period than those used to build it. It sits between reusing the development data and fully external testing in a new place.
Because medicine, coding practices, and patient mix drift over time, a model built on older patients may calibrate poorly on newer ones. Testing on a more recent slice of the same setting probes that drift while holding location roughly constant. It is a useful but partial check, since it does not reveal whether the model travels to different institutions or populations.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.