Figure 1. Relationship of positive predictive value (PPV) and prevalence shown for three combinations of sensitivity (Sn) and specificity (Sp)
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Figure 2. 95-percent confidence limits around sensitivity and positive predictive value (PPV) for various levels of prevalence and sample sizes.
Note: Sensitivity and specificity were set at 50 percent and 95 percent, respectively. Waves in lines are caused by rounding values to integers for computation of confidence intervals. Thick lines are the point estimates of each characteristic.
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