DFIT (version 1.1)

Ase2pl: Calculates the asymptotic covariance matrix of item parameter estimates under the 2pl model

Description

Calculates the asymptotic covariance matrix of item parameter estimates under the 2pl model

Usage

Ase2pl(
  itemParameters,
  distribution = "norm",
  distributionParameters = list(mean = 0, sd = 1),
  logistic = TRUE,
  sampleSize = 1,
  subdivisions = 5000
)

Arguments

itemParameters

A matrix or vector containing the item difficulties.

distribution

A string character indicating the generic name for the assumed distribution.

distributionParameters

A list of extra parameters for the distribution function.

logistic

A logical indicating whether the logistic or the normal metric should be used.

sampleSize

A value indicating the sample size.

subdivisions

A numeric value stating the maximum number of subdivisions for adaptive quadrature.

Value

ase A list containing the asymptotic matrices for each item

References

Li, Y. & Lissitz, R. (2004). Applications of the analytically derived standard errors of Item Response Theory item parameter estimates. Journal of educational measurement, 41(2), 85--117. doi:10.1111/j.1745-3984.2004.tb01109.x