Is a matchup contrast well defined?

A forced-choice contrast requires candidates A and B to be mutually exclusive: they must pin at least one shared attribute to different levels. Otherwise a single profile can satisfy both sides, the matchup includes tasks where the two candidates are identical on the pinned attributes, and the outcome reflects display position rather than any real difference.

Usage

valid_contrast(A, B)

Arguments

A, B

Named lists mapping attribute stems to pinned levels.

Value

TRUE if the contrast is well defined, FALSE otherwise.

See also

contrast_message(), get_matchups()

Examples

valid_contrast(list(party = "R"), list(party = "D"))   # TRUE
#> [1] TRUE
valid_contrast(list(party = "R"), list(gender = "F"))  # FALSE (no shared attr)
#> [1] FALSE
valid_contrast(list(party = "R"), list(party = "R"))   # FALSE (identical)
#> [1] FALSE