# Evaluation of clinical prediction models (part 3): calculating the sample size required for an external validation study

“Evaluation of clinical prediction models (part 3): calculating the sample size required for an external validation study” (2024), by Richard D Riley et al. Mathematics research paper. Original abstract below, unchanged. A free PDF is available.

- Authors: Richard D Riley, Kym I E Snell, Lucinda Archer, Joie Ensor, Thomas P. A. Debray, Ben VAN CALSTER, Maarten van Smeden, Professor Gary S. Collins
- Published: January 22, 2024
- Field: Mathematics
- DOI: https://doi.org/10.1136/bmj-2023-074821
- Free PDF: https://lirias.kuleuven.be/retrieve/e15a0a3b-12f6-43f7-8bdc-2bcdfde5d346

## Abstract

An external validation study evaluates the performance of a prediction model in new data, but many of these studies are too small to provide reliable answers. In the third article of their series on model evaluation, Riley and colleagues describe how to calculate the sample size required for external validation studies, and propose to avoid rules of thumb by tailoring calculations to the model and setting at hand.

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