Misc

Question 1

Formula PPV (PV+)

Answer 1

p(D+ | Test)

• PPV* = True Positives / (True Positives + False Positives)
• PPV* = (p(D+) * Se ) / (p(D+) * Se + p(D-)*(1-Sp))

Question 2

Formula NPV (PV-)

Answer 2

p(D- | Test-)

NPV = True Negatives / (True Negatives + False Negatives) [i.e. True Neg / ALL Neg]

NPV = (p(D-) * Sp ) / ((p(D-) * Sp + p(D-)*(1-Se))