[Rasch] Rasch model affected by item type or not

Rense Lange rense.lange at gmail.com
Fri Mar 12 04:31:56 EST 2010


Item later in the test tend to be affected due to fatigue, running out of
time, etc. and short tests are more sensitive to changes in items. But,
other than that, items won't change their relative locations regardless what
else is in the test. There may be random error. Just take any Rasch data
set, calibrate all items, then rerun with some items removed. Unless very
few items remain, a scatter plot of the non-removed items in these two cases
will parallel Y=X.

On 3/10/10, Parisa Daftari Fard <pdaftaryfard at yahoo.com> wrote:
>
>   Dear Rasch list members,
> Hi
>
> I came up with a question and I hope to have your reply. Does test
> configuration (the ordering of the item types and the adding or subtracting
> the item types) affect Rasch outcome in terms of the hierarchical order in
> item map?
>
> Does Rasch approach the item generically or pragmatically? by Generic I
> mean that adding one item type (not the total number but the cognition
> related item type) would not affect the pattern of items because the
> statistics is doing something on the nature of the item.
>
> I am not sure if I am clear?
>
> Best,
> Parisa
>
>
> _______________________________________________
> Rasch mailing list
> Rasch at acer.edu.au
> https://mailinglist.acer.edu.au/mailman/listinfo/rasch
>
>


-- 
Rense Lange, Ph.D.
via gmail

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