“…As compared to the exact approach for sample size calculation, (Lloyd, 2007, 2014, 2008a; Shan, 2013; Shan, Ma, Hutson, & Wilding, 2012; Shan & Ma, 2016; Shan, 2015; Shan, Wilding, Hutson, & Gerstenberger, 2016; Shan, Moonie, & Shen, 2016; Shan, 2015), the existing GEE approach does not guarantee type I and II error rates although it is computationally easy with a closed form. With the wide availability of powerful computers or supercomputers, exact sample size computation is practical and feasible.…”