Builds a family of intercation contrasts for complete two-factorial designs.
a vector of two character strings, specifying the contrast
a vector of two integers, specifying the number of groups in each factor of the two-factorial design
Creates contrast matrices using
contrMat from package multcomp, creates the kronecker product of both and creates suitable columnnames.
A matrix with k*k columns and a number of rows depending on type.
for 2-way interaction contrasts directly based on 2 contrasts matrices, see
two possibilities to specify appropriate rownames are implemented in function
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