Define a frame-native model design — design

A design specification preserves formulas and their environments. It does not freeze a model matrix: coding, missing-value handling, and multivariate block expansion occur when the specification is compiled against a frame.

Usage

design_spec(
  fixed,
  random = NULL,
  contrasts = NULL,
  na_action = c("fail", "omit")
)

Arguments

fixed: One-sided fixed-effects formula.
random: Optional one-sided random-effects formula.
contrasts: Optional named contrast list passed to [stats::model.matrix()].
na_action: Missing-value policy, either `"fail"` or `"omit"`.

Value

A serializable `design_spec`.