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Extract item parameter estimates and their covariance matrix from mirt.

get_mirt_pars.Rd

Extract item parameter estimates and their covariance matrix from mirt.

Usage

get_mirt_pars(mirt.object, cluster = NULL)

Arguments

mirt.object

a mirt object of class SingleGroupClass or MultipleGroupClass. Expected to be a 1-factor model with SE = TRUE and itemtype of any combination of "2PL", "graded", or "gpcm".

cluster

optional cluster-ID vector used to compute a cluster-robust covariance matrix using Oakes bread, empirical score outer products aggregated by cluster, and a CR1 finite-sample correction.

Value

A three-element list:

  • vector of parameter names taking the form "item.parameter"

  • list (one element per group) of vectors of item parameter estimates

  • list (one element per group) of covariance matrices of item parameter estimates