
38 Sample Size Calculations for Clustered and Longitudinal Outcomes
2.5 Two–Sample Clustered Binary Outcomes
In an innovative cancer risk intake system (CRIS) trial, physicians are ran-
domly allocated to either a comparison group or a risk–based innovative can-
cer risk intake system (CRIS) group that delivers patient-tailored print–outs
based on personal risk factors and perceived barriers to colon cancer testing
[27]. In this CRIS trial, a physician corresponds to a cluster. Based on assign-
ment of his or her physician, each patient will be assigned either to the CRIS
intervention or the comparison group, in which patients and physicians will
receiv ...