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Figure 3. Results of the simulation study of logistic regression models by Peduzzi et al. Pedduzi et al. (9) studied the stability of logistic regression coefficients under a variety of events-per-predictors ratios. Recall that the limiting sample size for a logistic model is the number of events (when there are fewer events than nonevents). The x-axis represents the ratio of events per predictor in the model for the case of 7 predictors. The y-axis shows the percent relative bias in the regression weight compared with the known population weight. The results suggest that bias is unacceptably high when there are fewer than 10 to 15 events per predictor. Reproduced with permission (9).
