pcIRT (version 0.1)

dLRT: Dimensionality test for the multidimensional polytomous Rasch model

Description

This function tests whether the multidimensional polytomous Rasch model can be reduced to a unidimensional polytomous model.

Usage

dLRT(MPRMobj)
## S3 method for class 'dLR':
summary(object, \dots)
## S3 method for class 'dLR':
print(x, \dots)

Arguments

MPRMobj

Object of class MPRM

object

object of class dLR

x

{object of class dLR}

...

...

Value

• emp_Chi2
  $\chi^2$ distributed value of the Likelihood Ratio test
• df
  degrees of freedom of the test statistic
• pval
  p value of the test statistic

Details

For this test, a unidimensional model assuming the categories as linearly dependent is computed. Subsequently a Likelihood Ratio test is conducted.

References

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

See Also

MPRM LRT

Examples

#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)

res_dlrt <- dLRT(res_mprm)
summary(res_dlrt)