Main Effects of Water Stress and Sulphur Dioxide

Main effects of water and sulphur

The ANOVA table confirms the lack of any indication of an interaction, but the F-tests for the main effects of water stress and sulphur dioxide now support the main effects of these variables, according to the p < 0.05 convention. This is even in the presence of an non-significant interaction. Earlier, we saw that for the one-way ANOVA of Darwin’s maize data, the ANOVA table F-tests and the summary table t-tests produced identical p-values. But things are different for this ANOVA—while the p-value for the interaction is the same in both tables, the tests for the upper two rows disagree.