Model Formula

A formula is a list of identifiers and operators defining the model terms to be analysed. For example:
Variety + Nitrogenmain effects of Variety and Nitrogen
Variety . Nitrogeninteraction term for Nitrogen and Variety
Variety * Nitrogensame as Variety + Nitrogen + Variety.Nitrogen
The following operators are commonly used in model formulae:
+additionA+B+Cmain effects of A, B, and C
.interactionA.Binteraction of A and B
*cross-productA*Bis equivalent to A+B+A.B
/nestingA/Bis equivalent to A+A.B

The following operators can also be used in formulae. A full definition of their meaning is found in The Guide to GenStat® Release 7.1 - Part 1: Syntax and Data Management.
-subtraction
-/nested deletion
-*crossed deletion
//linkage of pseudo terms