Define a linear contrast using a formula expression.
Usage
contrast(form, name, where = NULL)
Arguments
- form
A formula describing the contrast.
- name
A character label for the contrast.
- where
An expression defining the subset over which the contrast is applied (default: NULL).
Value
A list containing the contrast specification.
Examples
# A minus B contrast
contrast(~ A - B, name="A_B")
#> contrast: A_B
#> A: ~A - B
# With subsetting
contrast(~ A - B, name="A_B_block1", where = ~ block == 1)
#> contrast: A_B_block1
#> A: ~A - B
#> where: ~block == 1