PPV_diagnostic_vs_screening
                        Plot PPV values for a diagnostic and a
                        screening group
PPV_heatmap             Plot PPV and NPV heatmaps
min_possible_prevalence
                        Show minimum possible prevalence given the test
                        characteristics
plot_cutoff             plot_cutoff Create a cutoff plot, showing the
                        healthy and sick distributions, and the
                        consequences of different cutoff points
remove_layers_cutoff_plot
                        remove_layers_cutoff_plot Remove layers from a
                        cutoff plot. This is useful to show how
                        different things are calculated (e.g.
                        Sensitivity)
