Calculation of Diagnostic Accuracy Measures

nondiseased population

negative test result

8550

positive test result

950

diseased population

positive test result

450

negative test result

50

p-value

0.95

measure

sensitivity

population statistics
total population	10000
nondiseased	9500
diseased	500
prevalence of disease	0.050000

sensitivity 95.% confidence interval
point estimation	0.900000
lower bound	0.869471
upper bound	0.924200

This Demonstration shows calculations of point estimations and confidence intervals for various accuracy measures of a diagnostic test for a disease. This is done for differing negative and positive test results of nondiseased and diseased populations and differing

p

-values for the estimations of the lower and upper bounds of the confidence intervals. The calculated measures are the sensitivity, the specificity, the positive predictive value (PPV), the negative predictive value (NPV), the (diagnostic) odds ratio (OR), the likelihood ratio for a positive test result (LR+) and the likelihood ratio for a negative test result (LR−). The measures can be selected using the menu. The negative and positive test results of the nondiseased and diseased populations, along with the

p

-value, are chosen using the sliders.