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is a comparison of the effects (or parameter estimates) produced for the different levels of a treatment factor. If the factor levels correspond to different amounts x of a substance (for example a drug or a fertiliser), the POL function allows linear, quadratic, cubic or quartic polynomials of x to be fitted, or the REG function allows you to define your own regressions on x. Alternatively, the COMPARISON function allows comparisons to be defined between qualitative levels (ANOVA only).

Updated on June 18, 2019

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