[R] eRm package - Rasch simulation

[Achim Zeileis]

On Thu, 26 Jan 2012, James Holland wrote:

> When I try to create a Rasch simulation of data using the sim.rasch
> function, I get more items than I intend
>
> #My code
>
> library(eRm)
>
> #Number of items
> k <- 20
>
> #Number of participants
> n <- 100
>
>
> #Create Rasch Data
> #sim.rasch(persons, items, seed = NULL, cutpoint = "randomized")
>
> r.simulation <- sim.rasch(n,k)
>
> I end up with 20 participants and 100 items, but the instructions say
> otherwise (and I believe I have the most up to date).  I reverse the n and
> k

If I use your code above, I get

R> dim(r.simulation)
[1] 100  20

which is exactly as expected: 100 rows = persons and 20 columns = items.

This is with the current CRAN version of eRm: 0.14-0.
Z

> sim.rasch(k,n); it works out to how I intended; 100 participants and 20
> items.
>
>
> Can someone explain to me what I'm missing?  I've read the package
> instructions and didn't see myself missing something (inputting vectors
> instead of an integer).
>
> James
>
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