Build an Approved Model Formula — build_model

Constructs a backend-independent R formula from a create_model_contract() result. The formula records the approved fixed effects, one optional interaction, the participant grouping structure, an optional participant-level random slope, and an optional crossed item intercept.

Usage

build_model_formula(contract)

Arguments

contract: A gp3bayes_model_contract created by create_model_contract().

Value

An R formula. The formula is a specification only and has not been translated to, validated by, or fitted with a Bayesian backend.

Details

The participant random intercept is always included. When contract$random_slope is TRUE, it is replaced by a correlated participant intercept-and-condition-slope term. A declared item identifier adds a crossed item random intercept.

The trial identifier is treated as a row key and is not added as a predictor or grouping factor. A declared time column is included as a linear population-level term only.

Examples

contract <- create_model_contract(
  family = "binary",
  outcome_col = "selected",
  participant_col = "participant_id",
  item_col = "stimulus_id",
  condition_col = "condition",
  predictors = "age_z"
)

build_model_formula(contract)
#> selected ~ condition + age_z + (1 | participant_id) + (1 | stimulus_id)
#> <environment: base>