[Rasch] Rasch: analyze two versions of a test

Rense Lange rense.lange at gmail.com
Sun Jun 23 01:00:14 EST 2013


Is there any way to have two or more raters evaluate the same people on a fairly large scale? If so, you can also check rater effects using Facets … Even if you had only very limited numbers of double/triple/ … ratings, large rater differences/biases would be a sign for caution.

Rense Lange

On Jun 22, 2013, at 8:17 AM, "Bond, Trevor" <trevor.bond at jcu.edu.au> wrote:

> Dear Lucia
> You do it both ways, expecting invariance.
> Where you don't, you look for reasons.
> Then choose.
> TGB
> 
> 
> Sent from 007's iPad
> 
> On 22/06/2013, at 12:19 PM, "Lucia Luyten" <Lucia.Luyten at arts.kuleuven.be> wrote:
> 
>> Hi
>> 
>> I have a question about analyzing two versions of a test. 
>> 
>> Say we have 130 items for a test. We make two versions of this test. In version A, we put items number 1 to 80 and in version 2 the items number 50 to 130. So items 50-80 are in both versions. In version A, the item numbers 1 to 30 are anchor items from a previous test. For these items, we know and use the measures from a previous Facets analysis. These anchor items (1-30) occur only in version A, not in version B.
>> 
>> About 400 candidates take version A, and about 250 take version B. The test is rated by 4 raters. Raters rate both versions, each test taker is rated by one random rater.
>> 
>> One might choose to take all candidates together for analysis. Or one can choose to first analyze version A separately (using the measures for the anchor items).  And then use the outcome, i.e. the measures for the identical items (number 50-80) and the measures for the raters, in the subsequent analyses of version B. 
>> 
>> Which way of analyzing is preferable and why is it?
>> 
>> Kind regards, 
>> 
>> Lucia Luyten
>> 
>> 
>> Lucia Luyten
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>> 
>> www.cteno.be
>> 
>> 
>> 
>>  
>>  
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