This Phase II SBIR proposal concerns the development of Pow!, PC software to compute sample size, statistical power, and confidence interval width for the design of biomedical studies. Based on our Phase I design specifications, Pow! will have a convenient user interface, emphasize graphical display and easy creation of numerical tables, and be applicable to a wide range of models and designs. Our program will operate under Microsoft Windows 3.1 so that customized tabular and graphical output can be exported to word processors or spreadsheets by the Windows DDE. Noteworthy features of Pow! will include extensive coverage of design methods for time-to-event and repeated measures studies, assessment of design sensitivity to shifts in parameters, (e.g. fewer patients or smaller effects than anticipated), and context- sensitive help facilities. Graphical displays can be two- or three- dimensional (e.g. traditional power curves, and contour or hidden line net plots of power versus effect size and sample size). Pow! will operate by generating command files to MLAB, comprehensive software we created for numerical, graphical, and symbolic calculation. This link will permit easy expansion of Pow! as new designs or design calculations appear.
