<b>GLIMMPSE</b>: Online Power Computation for Linear Models with and without a Baseline Covariate

<b>GLIMMPSE</b> is a free, web-based software tool that calculates power and sample size for the general linear multivariate model with Gaussian errors (http://glimmpse.SampleSizeShop.org/). <b>GLIMMPSE</b> provides a user-friendly interface for the computation of power and sample size. We consider models with fixed predictors, and models with fixed predictors and a single Gaussian covariate. Validation experiments demonstrate that <b>GLIMMPSE</b> matches the accuracy of previously published results, and performs well against simulations. We provide several online tutorials based on research in head and neck cancer. The tutorials demonstrate the use of <b>GLIMMPSE</b> to calculate power and sample size.