Figure 1

Box-whisker plot. Box- and whisker plots provide a simple but also very powerful way to visualize the results of an ANOVA, and give an overview of five essential characteristics of a series of measurements including median, lower and upper quartiles, and extreme values. This figure demonstrates the differences between the calculated abundance ratios of four proteins. Both the ANOVA as well as the Kruskal-Wallis test show a significant change in abundance of the protein P40780 in experiment A. Although the measurements are not following a Gaussian distribution, there is clearly a differential regulation over time. The membrane protein Q01625 reveals only small changes. It was nonetheless regarded significant by the Kruskal-Wallis test, but not by the ANOVA after p-value adjustment. P39126, a NADP-dependent dehydrogenase, is not showing any clearly distinguishable and significant pattern of expression. A reason therefore might be a high biological variance but, of course, also technical errors in measurement. Fortunately, the same-albeit to an even greater degree--applies for the human protein K1C10, which is obviously a contamination.