Believe it or not, data analysis is as dreaded by science majors as it is by business majors. GraphPad’s InStat steps students and statistical dilettantes through entering data into a spreadsheet-like table and selecting the appropriate statistical test. Just as important, InStat completes the process by explaining data analysis.
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The new Mac OS X-ready version, 3.0, adds some new features: it now handles multiple regression, performs normality testing on data distributions, calculates correlation matrices, and indicates both sensitivity and specificity of each statistical test. But the big new feature is the analysis checklist, a sort of interactive version of GraphPad founder Harvey Motulsky’s textbook Intuitive Biostatistics.
Rather than confront you with a blank table, InStat starts with a page of questions to determine which type of test will solve your problem. It then guides you in assembling your data into the correct type of table, and suggests the appropriate test (you can override InStat’s choice). Finally, it interprets your output. You don’t just get tables with p- and f-values — you get plain English analyses of results and their statistical significance.
Although InStat includes most traditional basic statistics tests (t-tests, ANOVA, nonparametric) it includes some surprisingly advanced tests. Taking advantage of the vast computing power available on even the cheapest new Macs, InStat is one of the few introductory programs to offer the computation-intensive Fisher’s exact test, an excellent tool for lab workers with small data sets. The Help system, completely overhauled from version 2.0, also gives an excellent brief introduction to Fisher’s test.
One minor annoyance in version 3.0 is that its complete rewrite for PowerPC optimization and OS X means that the new product doesn’t read InStat 2.0 files directly — you bring in old data by cutting and pasting data tables. Our other complaints are that InStat has minimal graphing abilities (GraphPad diverted the graphic tools into its high-end product Prism) and limited data handling (1,000 by 26 is the largest table), but these aren’t significant drawbacks for the intended occasional user.
Macworld’s Buying Advice
The analysis checklists in InStat put the program in a class of its own for statistics. While classic Mac favorites like StatView and JMP (both from SAS Institute) are friendly programs and handle a broader range of tests than InStat, they are far from foolproof. As a statistical analysis tool for occasional users with modest amounts of data, InStat is the best choice.
Getting to Yes: If you have a hazy idea of which statistics test does what, InStat uses simple multiple choice forms to pick the right test for your data.