Fig. 3

Histogram of predicted risk for each observation based on the original risk prediction model plus a one simulated predictor with an odds ratio of 1.5 and 5 % prevalence, and b five simulated predictors with odds ratios of 6 and 40 % prevalence. Green bars indicate a clinically distinct low risk group (predicted risk <3.0 %); brown bars indicate uninformative predicted risk (3.0–15.0 %); blue bars indicate a clinically distinct high risk group (predicted risk >15.0 %)