Statistical Accuracy of iPad Applications: An Initial Examination

With the recent advent of the iPad, statistics-related applications (apps) have begun development. Given their newness, statistical accuracy is a concern. This study assessed the accuracy of the following iPad apps: Data Explorer, StatsMate, Statistics Visualizer, and TC-Stats. Early and recent versions of Excel were also included for comparative purposes. Accuracy was considered in two ways. First, the National Institute of Standards and Technology Statistical Reference Datasets (StRD) were used to benchmark accuracy. Analyses included univariate summary statistics (means, standard deviations), analysis of variance (ANOVA; F statistics), and linear regression (regression coefficients, standard deviations). The log relative error was computed for each dataset (comparing the "certified" values from StRD against the app actual values). Second, Wilkinson's tests were conducted to assess app "pass" rates (rounding, scatterplot, univariate, regression, overall). The results suggest the following: (a) the most accurate app for summary statistics and for lower difficulty ANOVA datasets was StatsMate, (b) the most accurate app for average difficulty ANOVA datasets was Data Explorer, (c) no app was accurate for higher difficulty ANOVA datasets, (d) only Data Explorer could handle most regression models, and (e) Wilkinson pass rates for Data Explorer (79%) and StatsMate (58%) were highest. Overall, StatsMate compares favorably to Excel 97, early versions being similarly accurate. Much remains to be done to improve the statistical accuracy of these apps.