A Practical and Accurate Approximation for Carrying Out Repeated Measures Power Calculations.
Oftentimes consulting researchers are faced with generating power calculations for pilot designs that entail complex correlation/covariance structures. In many of these instances it is necessary for the statistician to elicit information pertaining to the correlation/covariance structure from researchers with little or no statistical background. We detail a simple strategy that seems to work well with clients for standard repeated measures normal based models. The algorithm is based solely on eliciting minimum and maximum values. The procedure allows a statistician to develop a "baseline" for parameter values used in the power calculations. We then illustrate how to proceed with the calculations using simulation techniques and normal based approximations.
Department of Biostatistics, 706 Kimball Tower, 3435 Main Street, University at Buffalo, Buffalo, NY 14214-3000.
Alan D
AD
Hutson
Consulting