Screening and Diagnostic Tests

Description: Short published article on positive and negative predictive values.

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Who created this resource: This is one of two articles published together in the British Medical Journal (BMJ) in 1994 by two very well-known British biostatisticians and educators, Douglas G. Altman (1948-2018), late professor of statistics in medicine at Oxford University, and J. Martin Bland (1947-), professor of health statistics at the University of York.

What does this resource offer
This is the second of two very short 1-page published articles. This one clearly explains what positive predictive values (PPV) and negative predictive values (NPV) are, how they are calculated, and how to interpret these diagnostics measures. It uses plain language and a small example. The relationships among predictive values, specificity, sensitivity and prevalence are explained.