score.mlteqc {equateMultiple}

Scoring of multiple forms

Description

Relates number-correct scores on multiple forms.

Usage

## S3 method for class 'mlteqc'
score(obj, method="TSE", D=1, scores=NULL,  se=TRUE, nq=30, 
  w=0.5, theta=NULL, weights=NULL, ...)

Arguments

obj

object of the class mlteqc returned by function multiec.

method

the scoring method to be used. This should be one of "TSE" (the default) for true score equating or "OSE" for observed score equating.

D

constant D of the IRT model used to estimate item parameters.

scores

integer values to be converted.

se

logical; is TRUE standard errors of equated scores are computed.

nq

number of quadrature points used to approximate integrals with observed score equating. Used only if arguments theta and weights are NULL.

w

synthetic weight for population 1. It should be a number between 0 and 1.

theta

vector of ability values used to approximate integrals with observed score equating.

weights

vector of weights used to approximate integrals with observed score equating.

...

further arguments passed to or from other methods.

Details

In this function common items are internal, i.e. they are used for scoring the test.

Value

A data frame containing theta values (only for true score equating), scores of the form chosen as base, equated scores of all other forms, and standard errors of equated scores.

Author(s)

Michela Battauz

References

Kolen, M.J. and Brennan, R.L. (2014). Test equating, scaling, and linking: methods and practices, 3nd ed., New York: Springer.

Ogasawara, H. (2001). Item response theory true score equatings and their standard errors. Journal of Educational and Behavioral Statistics, 26, 31–50.

Ogasawara, H. (2003). Asymptotic standard errors of IRT observed-score equating methods. Psychometrika, 68, 193–211.

See Also

multiec

Examples

data(est2pl)
# prepare the data
mods <- modIRT(coef = est2pl$coef, var = est2pl$var, display = FALSE)

# Estimation of the equating coefficients with the multiple item response function method
eqIRF<-multiec(mods = mods, base = 1, method = "irf")
summary(eqIRF)

# scoring using the true score equating method
score(eqIRF)

# scoring using observed score equating method, without standard errors
score(eqIRF, method = "OSE", se = FALSE)