
<table class="table table"><tr><td></td><td>target</td><td></td></tr><tr><td>Predicted</td><td>Event</td><td>No Event</td></tr><tr><td>Event</td><td>A</td><td>B</td></tr><tr><td>No Event</td><td>C</td><td>D</td></tr></table><p>The formulas used here are:
$$Sensitivity = A/(A+C)$$
$$Specificity = D/(B+D)$$
$$Prevalence = (A+C)/(A+B+C+D)$$
$$Positive Predictive Value = (sensitivity * prevalence)/((sensitivity*prevalence) + ((1-specificity)*(1-prevalence)))$$
$$Negative Predictive Value = (specificity * (1-pr