Calculate4plProb {DFIT}

Calculates the item success probability under the 4PL model.

Description

Calculates the item success probability under the 4PL model.

Usage

Calculate4plProb(thetaValue, itemParameters, logistic = TRUE)

Arguments

thetaValue

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

itemParameters

A matrix containing the numeric values of item discriminations on the first column, item difficulties on the second, item guessing parameters on the third, and item upper asymptote on the fourth

logistic

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

Value

probabilities A numeric matrix with the probabilities on each thetaValue for each item.

Author(s)

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

References

de Ayala, R. J., (2009). The theory and practice of item response theory. New York: The Guildford Press