CalculateItemDifferences: Calculates the differences between two item option...

In DFIT: Differential Functioning of Items and Tests

Description

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

Usage

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 <vhcervantesb at unal.edu.co>

DFIT documentation built on Aug. 17, 2021, 9:07 a.m.