Q1 Once I have the analysis for an experiment and I am particularly interested in a pre-planned comparison of treatments how can I use contrasts?
So we assume from this someone has designed, conducted and is analysing something like a One-way ANOVA or a factorial ANOVA typically with blocking. So how can we compare certain treatments with others or a group of treatments with another.
Example would be compare a genotype A with the mean of B, C and D.
To do this we need to make an orthogonal contrast, and the Demonstration of this is downloadable here (Contrast)
To interpret this – we consider our contrast to be asking a particular question about the treatment structure and we are in fact dividing up our degrees of freedom for that factor into a particular question.
(Add an example R code and output)
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