mirtCAT custom first item

[Aaron Kaat]

So I see on the mirtCAT wiki page a custom next item function that uses person properties to vary the next item selection (http://philchalmers.github.io/mirtCAT/html/sim-unidimensional_custom.html). Is there a way to do that with the first item? For example, starting age 5 and item #1 and age 8 at item 18 --- or using one of the criteria, starting age 5 and the MPWI for theta = -0.5 and starting age 8 at the MPWI for theta = 0.25? Or something like that? It looks like the custom item selection can only affect subsequent items, not the first one, based on person properties. 

Aaron

[Phil Chalmers]

I treat starting items slightly different for reasons that many of the selection algorithms simply fail without any item response information. That said, the 'start_item' argument sounds like what you are after, so just create a vector of starting items for each individual prior to running mirtCAT() in whatever way you feel is appropriate. HTH.

Phil

On Fri, Jul 14, 2017 at 2:53 PM, Aaron Kaat <aaron...@gmail.com> wrote:

So I see on the mirtCAT wiki page a custom next item function that uses person properties to vary the next item selection (http://philchalmers.github.io/mirtCAT/html/sim-unidimensional_custom.html). Is there a way to do that with the first item? For example, starting age 5 and item #1 and age 8 at item 18 --- or using one of the criteria, starting age 5 and the MPWI for theta = -0.5 and starting age 8 at the MPWI for theta = 0.25? Or something like that? It looks like the custom item selection can only affect subsequent items, not the first one, based on person properties. 

Aaron

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