[Rasch] Rasch model affected by item type or not

Parisa Daftari Fard pdaftaryfard at yahoo.com
Fri Mar 12 17:45:53 EST 2010



Thank you for your and Rense's reply. 
 
By item type, any kind of item theoretically measures one part of unidimentional construct. For example in reading comprehension, one item measures main idea and one measures guessing or factual question or any other kind of item. Do you think learning would change the item location in Rasch scale? Does anyone know about any research in this respect. 
 
Or let me say in Agustin's term. Agustin mentions 
 
" it is expected that before and after intervention you shall move all the items in the same direction and the relative position will remain. But if it is not the same construct (competencies for elderly persons) then after intervention some trait must improve (physical capability to move an arm) and other must reduce (incontinency), the relative position will change and this will reflect the quality and usefulness of the intervention. "
 
Can we say that we do have a static competence. What if interactional competence or dynamic nature of competence in a chaos/complexity model be correct. Is always main idea more difficult than factual question. In a single test we (i and Rense Lange) did not come up with this result http://www.rasch.org/rmt/rmt232.pdf
 
Therefore, do you think that any construct can have a static nature to show a single pattern after and before intervention in Rasoul's term?
 
 
 
Best,
Parisa

--- On Thu, 3/11/10, iasonas <liasonas at cytanet.com.cy> wrote:


From: iasonas <liasonas at cytanet.com.cy>
Subject: RE: [Rasch] Rasch model affected by item type or not
To: "'Rense Lange'" <rense.lange at gmail.com>, "'Parisa Daftari Fard'" <pdaftaryfard at yahoo.com>, Rasch at acer.edu.au
Date: Thursday, March 11, 2010, 10:07 PM



i agree with Rense, but just a friendly word of caution.
 
If by item "type" you mean the format of the item i.e. multiple choice or short response, then in many cases this may affect the results a little bit because the item may tap on a slightly different dimension. I am trying to say that what Rense suggests happens only the model-data fit is practically satisfactory; otherwise, invariance does not hold
 
thank you
--- On Thu, 3/11/10, iasonas <liasonas at cytanet.com.cy> wrote:


From: iasonas <liasonas at cytanet.com.cy>
Subject: RE: [Rasch] Rasch model affected by item type or not
To: "'Rense Lange'" <rense.lange at gmail.com>, "'Parisa Daftari Fard'" <pdaftaryfard at yahoo.com>, Rasch at acer.edu.au
Date: Thursday, March 11, 2010, 10:07 PM



i agree with Rense, but just a friendly word of caution.
 
If by item "type" you mean the format of the item i.e. multiple choice or short response, then in many cases this may affect the results a little bit because the item may tap on a slightly different dimension. I am trying to say that what Rense suggests happens only the model-data fit is practically satisfactory; otherwise, invariance does not hold
 
thank you



From: rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au] On Behalf Of Rense Lange
Sent: Thursday, March 11, 2010 7:32 PM
To: Parisa Daftari Fard; Rasch at acer.edu.au
Subject: Re: [Rasch] Rasch model affected by item type or not


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

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