Figure 4

Comparison of logistic regression models based on simulated data. The predictor (number of exposures) was raw, categorical and transformed exposures in the model A, B and C, respectively. (a) indicated that the infectivity was 2% and the population prevalence was 10%, (b) indicated that the infectivity was 2% and the population prevalence was 20%, whereas (c) indicated that the infectivity was 2% and the population prevalence was 40%.