pcIRT (version 0.1)

simMPRM: simulate data according to MPRM

Description

With this function data sets according to the multidimensional polytomous Rasch model (MPRM) are simulated

Usage

simMPRM(itempar, persons = 500, seed = NULL)

Arguments

itempar

a matrix with item category parameters; each row represents a category and each column an item (see details)

persons

an integer representing the number of persons (observations) of the data set (see details)

seed

a seed for the random number generated can optionally be set

Value

• datmat
  simulated data set
• true_itempar
  the fixed item parameters according to the input
• true_perspar
  the fixed person parameters

Details

Data are generated with category values starting with 0. Thus the first row of the matrix containing the item parameters is matched to the category value 0 and so on. The last category is the reference category. Please note, that the item category parameters of the last category have to be 0 (due to parameter normalization)!

Person parameters are generated by a standard normal distribution.

References

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

Rasch, G. (1961). On general laws and the meaning of measurement in psychology, Proceedings Fourth Berekely Symposium on Mathematical Statistiscs and Probability 5, 321-333.

See Also

simCRSM

Examples

#set item parameters
item_p <- rbind(matrix(c(-1.5,0.5,0.5,1,0.8,-0.3, 0.2,-1.2), ncol=4),0)

#number of persons
pn <- 500

#simulate data set
simdatM <- simMPRM(item_p, pn)