 Screening tests are often evaluated using metrics such as sensitivity, specificity, and predictive values. These metrics are useful in understanding the accuracy of a test, however, they can be misinterpreted or misapplied. This article provides clarifications on the definitions of these metrics and explains why they may be misunderstood or misused. It also discusses the importance of providing information about all four metrics when evaluating a screening test. Finally, it emphasizes the need for consumers of health research to understand the metrics and their implications for making informed decisions regarding screening tests. This article was authored by Robert Trevethen.