Fit a multiple-response process-IRT reference model — fit_multiple_response_process

The bundled reference treats option selections as repeated binary outcomes with option-specific random difficulty/discrimination and optional gaze. This preserves option-level observations but does **not** reproduce the 2026 MRM/MRM-LD likelihood. Use `engine = "external"` for a validated exact implementation of a multiple-response model with inter-option dependence.

Usage

fit_multiple_response_process_irt(
  data,
  selected = "selected",
  theta = "theta",
  person = "participant_id",
  item = "item_id",
  option = "option_id",
  gaze = NULL,
  engine = c("reference", "external"),
  external_engine = NULL,
  ...
)

Arguments

data: Long person-item-option table.
selected: Binary option-selection indicator.
theta: Supplied latent-trait estimate/score.
person, item, option: Identifiers.
gaze: Optional option-level process measure.
engine: `reference` or `external`.
external_engine: Validated external fitter.
...: Arguments passed to the external engine.