Calculates the differences between two item option characteristic curves for all options (minus one).

Share:

Description

Calculates the differences between two item option characteristic curves for all options (minus one).

Usage

1
2
CalculateItemDifferences(thetaValue, itemParameters, irtModel = "2pl",
  logistic = TRUE)

Arguments

thetaValue

A numeric value or array for the theta (ability) value(s) for which the difference will be calculated

itemParameters

A list containing "focal" and "reference" item parameters. Item parameters are assumed to be on the same scale. Item parameters for each group should me a matrix with nrow equal to the number of items.

irtModel

A string stating the irtModel to be used. Should be one of "1pl", "2pl", "3pl", "grm" or "pcm".

logistic

A logical value stating if the IRT model will use the logistic or the normal metric.

Value

difference A numeric matrix with the differences on probabilities or on expected score for each item between focal and reference groups.

Author(s)

Victor H. Cervantes <vcervantes at icfes.gov.co> <vhcervantesb at unal.edu.co>

Want to suggest features or report bugs for rdrr.io? Use the GitHub issue tracker.