Build Helmert orthonormal contrasts — helmert

Creates orthonormal Helmert contrast matrices for a set of factors, suitable for use with effect-coded kernels. The resulting contrasts are orthonormal, which can improve numerical stability.

Usage

helmert_contrasts(Ls)

Arguments

Ls: Named integer vector specifying the number of levels per factor

Value

Named list of orthonormal contrast matrices, each of dimension L x (L-1) where L is the number of levels for that factor. Each matrix has orthonormal columns.

Examples

contrasts <- helmert_contrasts(c(A=3, B=4))
print(dim(contrasts$A))  # 3 x 2
#> [1] 3 2
print(dim(contrasts$B))  # 4 x 3
#> [1] 4 3