Why preserve the response process?

Multiple-response items can contain substantially more information than a single total or partial-credit score. A participant who selects A + C and a participant who selects B + D may receive the same conventional score while showing very different option-level response and visual-inspection patterns. The 0.7 development layer therefore preserves response combinations before any scoring rule is imposed.

long <- data.frame(
  participant_id = rep(c("p1", "p2"), each = 4),
  item_id = "item1",
  option_id = rep(c("A", "B", "C", "D"), 2),
  selected = c(TRUE, FALSE, TRUE, FALSE,
               FALSE, TRUE, FALSE, TRUE)
)
encode_response_combinations(long)
#>   participant_id item_id response_combination n_selected
#> 1             p1   item1                  A|C          2
#> 2             p2   item1                  B|D          2

Option-level process evidence

When option AOIs are available, the analysis can retain fixation/dwell evidence at exactly the same option level as selection. fit_multiple_response_process_irt() provides a transparent crossed-logistic reference model and an explicit external engine gate.

fit <- fit_multiple_response_process_irt(
  option_trials,
  selected = "selected",
  theta = "theta",
  item = "item_id",
  option = "option_id",
  gaze = "option_dwell_ms",
  engine = "reference"
)

The reference model is not the MRM/MRM-LD likelihood of Zhou and Guo. It is provided to establish the data contract, generate empirical diagnostics, and support validation before an exact implementation is connected. For a validated exact implementation, use engine = "external" and retain engine/version provenance.

Local dependence must be checked

Inter-option local dependence can invalidate an analysis that treats option responses as conditionally independent. If residuals from the response model are available, audit_process_local_dependence() provides a Q3-style pairwise diagnostic. An aligned process-residual matrix can be supplied to ask whether response and gaze residual dependence show the same pair structure.

set.seed(1)
r <- matrix(rnorm(400), ncol = 4,
            dimnames = list(NULL, paste0("option", 1:4)))
p <- r + matrix(rnorm(400, sd = .3), ncol = 4)
ld <- audit_process_local_dependence(r, p)
head(ld$pairs)
#>     first  second response_residual_correlation response_flag
#> 1 option1 option2                 -0.0009943199         FALSE
#> 2 option1 option3                  0.0183821868         FALSE
#> 3 option2 option3                 -0.0495362135         FALSE
#> 4 option1 option4                 -0.0504370615         FALSE
#> 5 option2 option4                 -0.0584224680         FALSE
#> 6 option3 option4                  0.1107803403         FALSE
#>   process_residual_correlation process_flag concordant_direction
#> 1                  0.006688086        FALSE                FALSE
#> 2                  0.055551769        FALSE                 TRUE
#> 3                 -0.083047142        FALSE                 TRUE
#> 4                 -0.013512184        FALSE                 TRUE
#> 5                 -0.073464541        FALSE                 TRUE
#> 6                  0.030193207        FALSE                 TRUE
plot(ld)

The threshold is descriptive. It is not a universal significance cutoff and must be interpreted with the fitted model, item design, multiplicity, and a simulation-calibrated null distribution.

Revisiting as collateral evidence in cognitive diagnosis

Current process-data work also shows that response time and item revisiting can be modeled alongside cognitive-diagnosis responses. The eyeprocess adapter keeps mastery semantics anchored to the supplied Q-matrix and uses revisiting, RT, and optional gaze variables as collateral process evidence.

cdm <- fit_revisit_process_cdm(
  response_matrix = Y,
  q_matrix = Q,
  process_data = process_log,
  person_id = "participant_id",
  revisited = "revisit_count",
  rt = "response_time_ms",
  gaze = c("stem_dwell_ms", "option_transition_count")
)

A process association must not be interpreted as a diagnosis of motivation, misconduct, or cognitive state. The appropriate scientific question is whether the process channel improves validated measurement or classification under pre-specified external/grouped validation.

Validation requirements

Before either model family is promoted, include at least response/attribute recovery, local-dependence misspecification, option sparsity, process-channel ablation, negative controls, and held-person/item/session/device validation. Use irt_validation_spec(), stress_test_local_dependence(), process_channel_ablation(), and grade_model_evidence() to retain a common evidence record.