transformTo500: Transform IRT parameters to another metric

In eatTrend: Estimate National Trends in International Large-Scale Assessments

Description

This function transforms IRT parameters to an arbitrary metric.

Usage

transformTo500(pars, mRefPop=NULL, sdRefPop=NULL, mtT=500, sdtT=100, 
wgts=NULL, type=c("itPar", "persPar"), cutScores=NULL)

Arguments

pars	A data frame containing the parameter estimates. The first column has to be an ID variable, the second column contains the estimates.
mRefPop	Numeric. The mean of the reference population.
sdRefPop	Numeric. The standard deviation in the reference population.
mtT	Numeric. Mean of arbitrary metric to which parameters are transformed.
sdtT	Numeric. Standard deviation of arbitrary metric to which parameters are transformed.
wgts	A vector containing the case weights.
type	Character. If itPar, a constant of log(0.625/0.375) will be added to the parameters. If persPar, no additional constant will be added.
cutScores	Named vector indicating the proficiency level cut scores in descending(!) order. If is not NULL, the function addCuts will be called.

Value

A data frame containing the transformed parameters.

Author(s)

Karoline Sachse

eatTrend documentation built on May 2, 2019, 4:46 p.m.