Sample size and power for McNemar's test with clustered data.

McNemar's test is used to compare the distribution of two paired binary random variables. When the data are clustered adjustment is needed to ensure that it is still a valid test. This article presents two approximations for calculating the power and sample size for the adjusted McNemar's test for clustered data, working with a particular adjustment. A simulation study is conducted to demonstrate the accuracy of these approximations. The method is also applied to the design of a study involving positron emission tomography in detecting metastatic colorectal cancer and sensitivity of sample size computations to the design parameters are explored in this context. Copyright 2004 John Wiley & Sons, Ltd.