[Rasch] Help! TAM question

Rense Lange rense.lange at gmail.com
Sun Jan 26 09:46:29 AEDT 2020


Ricardo,

Thanks for your helpful response! The error was in the third factor, the line should be:

	F3=~ 1*I31__I40

i.e., the last I (in I40) was missing

Rense


> On Jan 25, 2020, at 11:50 PM, Rense Lange <rense.lange at gmail.com> wrote:
> 
> Is there anyone here familiar with TAM? I am trying to fit a 3 dim model, using the lavaan method … the data are in “resp”
> 
> Based on the 2-dim example in the (terse) documentation, I am trying the code:
> 
> 
> tammodel <- "
>   LAVAAN MODEL:
>     F1=~ 1*I1__I20
>     F2=~ 1*I21__I30
>     F3=~ 1*I31__40
>     # Alternatively to the factor 1 one can use the item type Rasch
>     F1 ~~ F1
>     F2 ~~ F2
>     F3 ~~ F3
>     F1 ~~ F2
>     F1 ~~ F3
>     F2 ~~ F3
>     "
>     
> model3fac <- TAM::tamaan( tammodel, resp, irtmodel = "RSM", control=list(maxiter=200))
> 
> summary(model3fac)
> 
> Although the 2-dim version works fine, this one doesn’t. I get:
> 
> Error in seq.default(which(items == v10[1]), which(items == v10[2])) : 
>   'to' must be of length 1
> 
> Does anyone know?

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