has part denotes graph axis Fagan nomogram Fagan nomogram is a graph plotting pre-test probabilities, likelyhood ratios and post-test probabilities on 3 parallel axis. The plot was first proposed by Fagan in 1975 as a way to visualize Baye's Theorem data where P(D) is the probability that the patient has the disease before the test. P(D|T) is the probability that the patient has the disease after the test result. P(T|D) is the probability of the test result if the patient has the disease, and P(T|D̄) is the probability of the test result if the patient does not have the disease. With this terminology the usefulness of both positive and negative test results can be assessed. A line drawn from P(D) on the right through the ratio of P(T|D) to P(T|D̄) gives P(D|T) on the left of the nomogram. Philippe Rocca-Serra http://www.ncbi.nlm.nih.gov/pubmed/1143310 N Engl J Med 1975; 293:257July 31, 1975 DOI: 10.1056/NEJM197507312930513 likelihood ratio pretest probability ready for release