Assessing the reliability of web-based statistical software

Statistical reference datasets from the National Institute of Standards and Technology were used to evaluate the accuracy and precision of two web-based statistical packages, WebStat (found at http://www.stat.sc.edu/webstat/) and Statlets (found at http://www.statlets.com/statletsindex.htm). This evaluation revealed that both packages performed reasonably well in the analysis of lower difficulty datasets, with decreasing accuracy as difficulty increases. The decrease in accuracy for datasets of higher difficulty can often be contributed to the dataset storage format (which seems to be single precision in Statlets and is double precision in WebStat). For most statistical analysis needs, the level of accuracy found in WebStat and Statlets would likely be unsatisfactory. Limitations of the packages are discussed and comparisons of accuracy with commercially available statistical packages are presented. WebStat and Statlets are user-friendly packages that are amenable to use as teaching tools. Thus we advise that the statistics packages we evaluated be restricted to use in teaching situations. They should not be used for the analysis of datasets with higher difficulty levels.