Epidemiology – Specificity and Sensitivity
The sensitivity and specificity of a new test are 60% and 70%, respectively. Three hundred people are screened at a clinic during the first year the new test is implemented. Assume the true prevalence of disease among clinic attendees is 10%. Set up the 2×2 table to calculate positive predictive value. (Hint: Use prevalence for determining marginal total of subjects who have the disease, TP+FN. Use this information and formulas for sensitivity and specificity to determine TP, FN, FP and TN).
Q.1 What is the predictive value of a positive test?
Q.2 And the number of true negative?