Research methods

Question 1

Sensitivity and specificity calculations

Answer 1

Sensitivity = TP/(TP+FN)
Specificity = TN/(TN+FP)

Sensitivity = true pos/all diseased
Specificity = true neg/all without disease

Question 2

Positive and negative predictive value calculations

Answer 2

PPV = TP/(TP+FP)
NPV = TN/(TN+FN)

PPV = true pos/total pos
NPV = true neg/total neg