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Re: question about measure creation statistics

Posted by Bruce Weaver on Nov 18, 2011; 9:21pm
URL: http://spssx-discussion.165.s1.nabble.com/question-about-measure-creation-statistics-tp5002888p5005617.html

It is KR-21, not KR-20, that assumes all items are equally difficult.  See Paul O's earlier post:

http://spssx-discussion.1045642.n5.nabble.com/question-about-measure-creation-statistics-tp5002888p5003728.html


ANDRES ALBERTO BURGA LEON wrote
KR-20 is for dichotomous scored items, asuming all have the same dificulty

Does all your items have the same dificulty?

Andrés

Mg. Andrés Burga León
Coordinador de Análisis e Informática
Unidad de Medición de la Calidad Educativa (UMC)
Ministerio de Educación del Perú
Av.de la Arqeuología s/n (cuadra 2)
Lima 41
Perú
Teléfono 615-5840 - 6155800 anexo 1212
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17/11/2011 09:31 p.m.
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Re: question about measure creation statistics






SPSS can calculate just about anything.  Please provide formula for KR-21
coefficient (I have not studied psychometrics for about 20+ years) and
don't
have the time to google it.

mmiesner wrote:
>
> Hello-
> I'm creating a measure that currently has 20 items. 18 of these items
are
> multiple choice, 4 possible answer questions. 2 of the items have 7
> possible answers. All of the items are covering the same broad area
> (knowledge of psychological disorder criteria).
>
> I ran cronbach's alpha and the score was .78.
> I talked to my advisor, who said this was incorrect and I should have
run
> KR-20. I did some reading, and two things appear to be true.
>
> First, that in fact, I should be using KR-21 since the answers are not
> dichotomous.
> Second, that there is no way to do this in SPSS.
>
> Would LOVE some guidance.
>
> Michael
>


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Bruce Weaver
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"When all else fails, RTFM."

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