Assessment of diagnostic tests when disease verification is subject to selection bias

In the assessment of the statistical properties of a diagnostic test, for example the sensitivity and specificity of the test, it is common to derive estimates from a sample limited to those cases for whom subsequent definitive disease verification is obtained. Omission of nonverified cases can seriously bias the estimates. In order to adjust the estimates it is necessary to make assumptions about the mechanism for selecting cases for verification. Methods for making the necessary adjustments can then be derived.