Re: question about measure creation statistics
Posted by
ANDRES ALBERTO BURGA LEON on
Nov 18, 2011; 9:06pm
URL: http://spssx-discussion.165.s1.nabble.com/question-about-measure-creation-statistics-tp5002888p5005618.html
Sorry for the last post, I've mixed
20 and 21.
Anyway, Both are for dichotoimous items,
and KR-20 is mathematically equivalent to Cronbachs alpha
Michael, you said:
> First, that in fact, I should
be using KR-21 since the answers are not
> dichotomous.
If your answres are not dichotomous
you should not be using any KR reliability estimate.
Cronbacdh alpha is both for dichotomous
and polytomous scored items.
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
http://www2.minedu.gob.pe/umc/
| "Swank, Paul R"
<[hidden email]>
18/11/2011 03:58 p.m.
|
|
Para
| ANDRES ALBERTO BURGA LEON <[hidden email]>
|
|
cc
|
|
|
Asunto
| RE: question about measure creation
statistics |
|
That’s the KR-21 that does
that. KR-20 assume that all items have the same relation to the true score.
Dr. Paul R. Swank,
Children's Learning Institute
Professor, Department of
Pediatrics, Medical School
Adjunct Professor, School
of Public Health
University of Texas Health
Science Center-Houston
From: SPSSX(r) Discussion [[hidden email]]
On Behalf Of ANDRES ALBERTO BURGA LEON
Sent: Friday, November 18, 2011 2:27 PM
To: [hidden email]
Subject: Re: question about measure creation statistics
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
http://www2.minedu.gob.pe/umc/
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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