AseIrt {DFIT}

Calculates the asymptotic covariance matrices for item parameters according with the IRT model.

Description

Calculates the asymptotic covariance matrices for item parameters according with the IRT model.

Usage

AseIrt(
  itemParameters,
  distribution = "norm",
  distributionParameters = list(mean = 0, sd = 1),
  logistic = TRUE,
  sampleSize = 1,
  irtModel = "3pl",
  subdivisions = 5000
)

Arguments

itemParameters

A matrix or vector containing the item difficulties.

distribution

A string character indicating the generic name for the assumed distribution. Defaults to 'norm' for normal 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.

irtModel

A string stating the IRT model for all items.

subdivisions

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

Value

ase A list containing the asymptotic matrices for each item

Author(s)

Victor H. Cervantes <vhcervantesb at unal.edu.co>

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

Examples

# # Not run
# #
# # data(dichotomousItemParameters)
# # threePlParameters <- dichotomousItemParameters
# # isNot3Pl          <- ((dichotomousItemParameters[['focal']][, 3] == 0) |
# #                       (dichotomousItemParameters[['reference']][, 3] == 0))
# #
# # threePlParameters[['focal']]          <- threePlParameters[['focal']][!isNot3Pl, ]
# # threePlParameters[['reference']]      <- threePlParameters[['reference']][!isNot3Pl, ]
# # threePlParameters[['focal']][, 3]     <- threePlParameters[['focal']][, 3] + 0.1
# # threePlParameters[['reference']][, 3] <- threePlParameters[['reference']][, 3] + 0.1
# # threePlParameters[['focal']][, 2]     <- threePlParameters[['focal']][, 2] + 1.5
# # threePlParameters[['reference']][, 2] <- threePlParameters[['reference']][, 2] + 1.5
# # threePlParameters[['focal']]          <- threePlParameters[['focal']][-c(12, 16, 28), ]
# # threePlParameters[['reference']]      <- threePlParameters[['reference']][-c(12, 16, 28), ]
# #
# # threePlAse <- list()
# # threePlAse[["focal"]]     <- AseIrt(itemParameters = threePlParameters[["focal"]],
# #                                     logistic = TRUE,
# #                                     sampleSize = 10000,
# #                                     irtModel = "3pl")
# # threePlAse[["reference"]] <- AseIrt(itemParameters = threePlParameters[["reference"]],
# #                                     logistic = TRUE,
# #                                     sampleSize = 15000,
# #                                     irtModel = "3pl")