# UNC Exam

The UNC Medicine Exam is based on topics covered in lectures during the first four week rotation: Diagnostic and Therapeutic Reasoning, CXR and EKG interpretation). It will be given at each clerkship site on the last day of the first four week rotation.

On the Exam, students may be asked to:

- explain in plain English the concepts of prevalence, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, pre-test probability and post-test probability
- explain the interrelationship between all of the above concepts (e.g., calculate each value when given several of the other values; describe which values change with prevalence of disease and which can be considered characteristics of the test itself)
- explain in plain English the concepts of action threshold, observe/test threshold and test/treat threshold
- convert from probability to odds and from odds to probability
- determine which test has the best ability to "rule in" or "rule out" a given disease when given sensitivity, specificity and likelihood ratios
- calculate likelihood ratios when given information in a 2 x 2 table format
- calculate likelihood ratios when given sensitivity and specificity
- calculate post-test probability when given pre-test probability and likelihood ratios (by using long-hand math and also by using Fagan nomogram)
- calculate post-test probability when given pre-test probability and several likelihood ratios (linking several LRs together)
- calculate action threshold for using treatment when given net benefit of treatment, harm of treatment and harm of disease
- calculate observe/test threshold and test/treat threshold when given action threshold and sensitivity and specificity of test
- recognize key EKG findings
- recognize key chest xray findings

Every concept on the Exam is listed above. Students who are able to do all of the above will do well on the Exam.