Abstract
In this article, I present an alternative formula for the calculation of a factorial analysis of variance (ANOVA), which requires only the mean, standard deviation, and size for each cell of the design, rather than the individual scores. This new method allows a modern hand-held calculator to do most of the work, while still giving students the educational experience of working directly with data. An example is given, in which the new method is applied to a published table of data from a two-way unbalanced ANOVA design. I argue that the new formula is not just easier to use than the traditional (raw-score) calculation formula (especially when dealing with higher order factorial designs), but that it is a better teaching tool, and it conveniently allows estimation of effect sizes from means and standard deviations even when the original authors do not present the corresponding F ratios. Although it seems that instructors are moving away from teaching ANOVA calculation in favor of focusing on the interpretation of computer output, I propose that students will learn more about the structure of ANOVA from using my new method than by avoiding hand calculation entirely (using only statistical software), or by performing calculations with the traditional method.