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Model Formula

A formula is a list of identifiers and operators defining the model terms to be analysed. For example:

Variety + Nitrogen Main effects of Variety and Nitrogen
Variety . Nitrogen Interaction term for Nitrogen and Variety
Variety * Nitrogen Same as Variety + Nitrogen + Variety.Nitrogen

The following operators are commonly used in model formulae:

+ Addition A+B+C Main effects of A, B, and C
. Interaction A.B Interaction of A and B
* Cross-product A*B Is equivalent to A+B+A.B
/ Nesting A/B Is equivalent to A+A.B

The following operators can also be used in formulae.

-/ Nested deletion
-* Crossed deletion
// Linkage of pseudo terms
Updated on February 1, 2019

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