wt: Test for the scoring weights in the unidimensional polytomous...
In pcIRT: IRT Models for Polytomous and Continuous Item Responses

Description Usage Arguments Details Value Author(s) References See Also Examples

This functions tests the fit of fixed scoring parameters in a unidimensional polytomous Rasch model.

## S3 method for class 'wt'
print(x, ...)

## S3 method for class 'wt'
summary(object, ...)

weight_test(MPRMobj, score_param)

`x`	object of class `wt`
`...`	...
`object`	object of class `wt`
`MPRMobj`	Object of class `MPRM`
`score_param`	Numerical vector with the scoring parameters that are tested

If the unidimensional polytomous Rasch model fits the data, the weight test can be performed to test whether assumed scoring parameters are appropriate. An unconstrained unidimensional polytomous Rasch model is calculated including estimation of scoring parameters. Furthermore a constrained unidimensional polytomous Rasch model is estimated with fixed scoring parameters (according to the input). Subsequently a Likelihood Ratio test tests the fit of the fixed scoring parameters.

`emp_Chi2`	χ^2 distributed value of the Likelihood Ratio test
`df`	degrees of freedom of the test statistic
`pval`	p value of the test statistic
`unconstrLoglikelihood`	log-likelihood of the unconstrained model
`constrLoglikelihood`	log-likelihood of the constrained model
`unconstrNrPar`	number of estimated parameters in the unconstrained model
`constrNrPar`	number of estimated parameters in the constrained model
`unconstrItempar`	estimated item parameters of the unconstrained model
`constrItempar`	estimated item parameters of the constrained model
`unconstrScoreParameter`	estimated scoring parameters of the unconstrained model

Christine Hohensinn

Fischer, G. H. (1974). Einfuehrung in die Theorie psychologischer Tests [Introduction to test theory]. Bern: Huber.

MPRM dLRT

#simulate data set
simdat <- simMPRM(rbind(matrix(c(-1.5,0.5,0.5,1,0.8,-0.3, 0.2,-1.2), 
                  ncol=4),0), 500)

#estimate MPRM item parameters
res_mprm <- MPRM(simdat$datmat)

#tests the scoring parameter 0.5 for the unidimensional polytomous model
res_weight <- weight_test(res_mprm,  score_param=c(0.5))
summary(res_weight)