Four hundred or more participants needed for stable contingency table estimates of clinical prediction rule performance

Objectives To quantify variability in the results of statistical analyses based on contingency tables and discuss the implications for the choice of sample size for studies that derive clinical prediction rules. Study Design and Setting An analysis of three pre-existing sets of large cohort data (n = 4,062–8,674) was performed. In each data set, repeated random sampling of various sample sizes, from n = 100 up to n = 2,000, was performed 100 times at each sample size and the variability in estimates of sensitivity, specificity, positive and negative likelihood ratios, posttest probabilities, o... Mehr ...