sim.rasch {eRm} R Documentation

## Simulation of Rasch homogeneous data

### Description

This utility function returns a 0-1 matrix which fits the Rasch model.

### Usage

sim.rasch(persons, items, seed = NULL, cutpoint = "randomized")


### Arguments

 persons Either a vector of person parameters or an integer indicating the number of persons (see details) items Either a vector of item parameters or an integer indicating the number of items (see details) seed A seed for the random number generated can be set. cutpoint Either "randomized" for a randomized tranformation of the model probability matrix into the model 0-1 matrix or an integer value between 0 and 1 (see details)

### Details

If persons or items is an integer value, the corresponding parameter vector is drawn from N(0,1). The cutpoint argument refers to the transformation of the theoretical probabilities into a 0-1 data matrix. A randomized assingment implies that for each cell an additional random number is drawn. If the model probability is larger than this value, the person gets 1 on this particular item, if smaller, 0 is assigned. Alternatively, a numeric probability cutpoint can be assigned and the 0-1 scoring is carried out according to the same rule.

### References

Su\'arez-Falc\'on, J. C., & Glas, C. A. W. (2003). Evaluation of global testing procedures for item fit to the Rasch model. British Journal of Mathematical and Statistical Society, 56, 127-143.

sim.xdim, sim.locdep, sim.2pl

### Examples


#simulating Rasch homogenous data
#100 persons, 10 items, parameter drawn from N(0,1)
X <- sim.rasch(100, 10)

#person parameters drawn from uniform distribution, fixed cutpoint
ppar <- runif(100,-2,2)
X <- sim.rasch(ppar, 10, cutpoint = 0.5)


[Package eRm version 1.0-2 Index]