Not just normal: Exploring power with Shiny apps

Abstract

Statistical power is an important topic taught in most graduate-level and undergraduate-level mathematical statistics courses, but it is often difficult to understand conceptually. Visualizing the power curve, sampling distributions, and how they interact can help students more easily conceptualize power, but the creation of such visuals can be difficult and time-consuming. Interactive web applications provide a way for students to dynamically visualize power, and many web applications for understanding power exist. However, most of these applications assume samples are drawn from a Normal population, concern only the sample mean, and/or were created for introductory classes. In this paper, we describe a web application suitable for undergraduate-level and graduate-level mathematical statistics courses that was created to allow users to visualize the complex relationships underlying power for multiple different statistics and population distributions (available at https://powerapp.shinyapps.io/powerapp/); source code is provided for instructors who wish to modify the application. Our experience implementing this application across two different semesters is also discussed, and example activities are provided in the appendix.