Sample Size and Power Calculations for Periodontal and Other Studies with Clustered Samples Using the Method of Generalized Estimating Equations

In this paper we provide sample size or power estimation formulas for clinical trials that involve clustered samples and intend to use the method of Generalized Estimating Equations (GEE) for data analyses. The general formulas and two special cases, one for continuous and another for binary variables are given. The motivating example of periodontal clinical trial is given for illustration. These formulas should help researchers in designing studies with appropriate sample size and power.

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