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This plot presents the mean signal-to-noise ratio of all the genes on the microarray. All the non-random factors in the ANOVA model are listed on the X-axis (including random error). The Y-axis represents the mean of the ratios of mean square of all the genes to the mean square error of all the genes. Mean square is ANOVA’s measure of variance. Compare each signal bar to the error bar; if a factor bar is higher than the error bar, that factor contributed significant variation to the data across all the variables. Notice, that this plot is very consistent with the results in the PCA scatter plot. In this data, on average, Tissue is the largest source of variation.

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