coef: S3 Methods: coef

In ForceChoice: Forced-Choice Modeling Based on Item Response Theory and Cognitive Diagnostic Models

S3 Methods: coef

Description

Extract estimated model coefficients (item, statement, or block parameters) from fitted ForceChoice model objects. This provides a standard R interface for retrieving parameter estimates, standard errors, and convergence diagnostics in a consistent format across all eight model families.

Usage

## S3 method for class 'MIRT'
coef(object, type = c("par", "theta", "Corr", "all"), ...)

## S3 method for class 'MGPCM'
coef(object, type = c("par", "theta", "Corr", "all"), ...)

## S3 method for class 'MGGUM'
coef(object, type = c("par", "theta", "Corr", "all"), ...)

## S3 method for class 'FCMIRT'
coef(object, type = c("par", "theta", "Corr", "all"), ...)

## S3 method for class 'FCDCM'
coef(object, type = c("par", "theta", "Corr", "all"), ...)

## S3 method for class 'FCGDINA'
coef(object, type = c("par", "theta", "Corr", "all"), ...)

## S3 method for class 'FCGGUM'
coef(object, type = c("par", "theta", "Corr", "all"), ...)

## S3 method for class 'TIRT'
coef(object, type = c("par", "theta", "Corr", "all"), ...)

Arguments

object	An object of one of the following classes: "MIRT" — Multidimensional IRT model. "MGPCM" — Multidimensional Generalized Partial Credit Model. "MGGUM" — Multidimensional Generalized Graded Unfolding Model. "FCMIRT" — Forced-Choice Multidimensional IRT model. "FCDCM" — Forced-Choice Diagnostic Classification Model. "FCGDINA" — Forced-Choice GDINA model. "FCGGUM" — Forced-Choice Generalized Graded Unfolding Model. "TIRT" — Thurstonian IRT for Forced-Choice.
type	Character string specifying which parameters to extract: "par" (default) for item/statement parameters, "theta" for person trait estimates, "Corr" for factor correlations, or "all" for a list with all three.
...	Additional arguments (currently ignored).

Details

For FCDCM objects, type = "par" returns a list with components delta (higher-order parameters, D \times 2) and par (block \eta parameters, B \times 2), reflecting the hierarchical structure of the model.

Value

type = "par"

A matrix of item/statement/block parameter estimates. Rows index items/statements/blocks and columns index parameter types. Column names indicate the parameter (e.g., "a1", "b", "d0", "tau1", "eta0").

type = "theta"

An N \times D matrix of person parameter (latent trait) estimates.

type = "Corr"

A D \times D inter-trait correlation matrix.

type = "all"

A named list with components par, theta, and Corr.

Methods (by class)

• coef(MIRT): Extract coefficients from MIRT objects. Returns I \times (D+3) matrix with columns a1..aD, b, c, d.

• coef(MGPCM): Extract coefficients from MGPCM objects. Returns I \times (D+K_{\max}) matrix with columns a1..aD, d0..d(K-1).

• coef(MGGUM): Extract coefficients from MGGUM objects. Returns matrix with columns a1..aD, delta1..deltaD, tau0..tau(K-1).

• coef(FCMIRT): Extract coefficients from FCMIRT objects. Returns statement parameter matrix with columns a1..aD, b, c, d.

• coef(FCDCM): Extract coefficients from FCDCM objects. Returns a list with delta (D \times 2 higher-order parameters) and par (B \times 2 block \eta parameters). type = "theta" returns the higher-order trait, and type = "Corr" returns a scalar 1.

• coef(FCGDINA): Extract coefficients from FCGDINA objects. type = "par" returns CDM delta parameters, type = "theta" returns posterior attribute mastery probabilities, type = "Corr" returns NA (no continuous latent trait).

• coef(FCGGUM): Extract coefficients from FCGGUM objects. Returns matrix with columns a1..aD, delta1..deltaD, tau0..tau(K-1).

• coef(TIRT): Extract coefficients from TIRT objects. Returns I \times (D+1) matrix with columns lambda1..lambdaD, psi2.

Examples

sim <- sim.data.MIRT(N = 20, I = 6, D = 2, model = "m2pl")
fit <- fit.MIRT(
  sim$response, model = "m2pl", D = 2, method = "iStEM",
  control.method = list(
    vis = FALSE, seed = 123,
    M = 2, B = 2, burnin.maxitr = 2,
    maxitr = 3, eps1 = 10, eps2 = 10,
    estimate.se = FALSE)
)

coef(fit)                  # item parameter estimates
coef(fit, type = "theta")  # person trait estimates
coef(fit, type = "Corr")   # factor correlation matrix
coef(fit, type = "all")    # everything in a list

ForceChoice documentation built on Sept. 13, 2026, 1:06 a.m.