[Rasch] Bunched versus spread out items to measure depression

Agustin Tristan ici_kalt at yahoo.com
Sun Jul 24 11:40:22 EST 2011


Hello Ian, in such case no need to use the Rasch model as no measures are obtained from Beck's questionnaire.
Regards
Agustin


INSTITUTO DE EVALUACION E INGENIERIA AVANZADA.

Ave. Cordillera Occidental No. 635
Colonia Lomas 4ª San Luis Potosí, San Luis Potosí.
C.P. 78216 MEXICO
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Página Web (en español): http://www.ieia.com.mx
Web page (in English): http://www.ieesa-kalt.com/English/Frames_sp_pro.html


--- On Sat, 7/23/11, Ian Wilson <I.Wilson at uws.edu.au> wrote:


From: Ian Wilson <I.Wilson at uws.edu.au>
Subject: RE: [Rasch] Bunched versus spread out items to measure depression
To: "Agustin Tristan" <ici_kalt at yahoo.com>, "Michael Lamport Commons" <commons at tiac.net>, "Rasch" <rasch at acer.edu.au>
Date: Saturday, July 23, 2011, 8:15 PM






Hi Agustin
The problem is that the Beck produces a dichotomous result – Depression Yes or No.  It does not produce levels of depression.  For that you need another instrument such as the K10 or DASS
Regards
Ian
 
Ian Wilson
Professor of Medical Education
School of Medicine
University of Western Sydney
Locked Bag 1797
Penrith NSW 2751
 
T: +61 2 4620 3678
F: +61 2 4620 3890
E: i.wilson at uws.edu.au
 
From: rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au] On Behalf Of Agustin Tristan
Sent: Sunday, 24 July 2011 11:05 AM
To: Michael Lamport Commons; Rasch
Subject: Re: [Rasch] Bunched versus spread out items to measure depression
 





Hello!

Sometimes I would like to have a better way to explain myself in English and try to transmit my ideas regarding the problem you're facing actually, I hope this time I shall be clear enough.

The idea of the design of a test is important for everyone and validity is the main and first property for many of us. Nevertheless I think we are not following a former idea by Ben Wright that is presented in several documents concerning the item distribution and all the implications this simple concept has regarding the other characteristics of measurement.

 

An investigator produces a test with N items for a specific construct (depression in this case), using partial credit, dichotomous or any other kind of items. He uses the questionnaire with M persons and passes the responses through the Rasch model using a good software (independently of the brand: Winsteps, Rumm, Rascal, your own software...) and he gets measures that are intended to be in a linear scale. The distribution of the measures of the persons or the individual measures will be interpreted according to the scale and the item measure will give some interpretation concerning depression in this case. This is ok...wait! is this ok? what is the problem with this? It is related to validity.

 

We have used the Beck depression questionnaire (and also the suicide scale and other scales), that are supposed to correctly measure depression (or suicide), but what we have found is that the Beck scale is satisfactory only for "depressed" people. But if we use it with what we could call "normal or non depressed " persons, then test is useless. 

Do I have to wait that my young students become depressed if we want to detect them with the Beck questionnaire?

Do I have to wait that my car tank is empty to decide that I have to go to the pump station?

 

The persons distribution, and the SE may say something but only if I am in a certain portion of the scale, because the questionnaire does not have items covering all the possible states from "normal" to pathologically depression. Ben Wright suggest to have items covering all the scale and not only a portion, unless I want to use the scale on depressed persons. 

Item distribution is related to the test design line, an idea proposed by Ben but not used everywhere and not conceptualized as a theoretical concept. 

I can notice that we accept the Rasch model as a theoretical expected model of an item and, curiously,  we do not accept that there should be also a theoretical expected model for a test (the test design line is that model). That is whay we can accept tests with a bad distribution of items, with a defficient scale, because we are convinced that the Rasch measures permit to define ALL the scale, even if the set of items is not sufficient to describe the construct.

 

Without the theoretical test model, we try to explain the problems with the Beck's measures (or the suicide, etc.) as a function of the SE, or probably as a consequence of the sample, or perhaps because we may think that it is not Guttmann, or probably because the Cronbach's alpha was 0.3, or probably because they copied the answers, or probably because we have to wait that our students become sufficiently depressed if we wish to measure them using Beck or Hamilton questionnaires... and all those explanations may be false, because the basics of the scale is wrong. 

 

I cannot understand how we can try to explain the planetary system unless we understand that the planets translate around the Sun. Everything about the planets comes from this concept, otherwise we can give explanations that are very complicated and someday will fail.

I cannot understand how we can try to explain the results of a test unless we use the test design line as a necessary coondition for the scale's validity. Everything about test and persons measures comes from this concept, otherwise we can give explanations that are very complicated and someday will fail.

 

I've presented the tests design line and all its implications elsewhere...It works.

 

Regards

Agustin

 

 

 

 

 



 

INSTITUTO DE EVALUACION E INGENIERIA AVANZADA.


Ave. Cordillera Occidental No. 635

Colonia Lomas 4ª San Luis Potosí, San Luis Potosí.

C.P. 78216 MEXICO

(52) (444) 8 25 50 76 / (52) (444) 8 25 50 77 / (52) (444) 8 25 50 78

Página Web (en español): http://www.ieia.com.mx

Web page (in English): http://www.ieesa-kalt.com/English/Frames_sp_pro.html


--- On Sat, 7/23/11, Michael Lamport Commons <commons at tiac.net> wrote:

From: Michael Lamport Commons <commons at tiac.net>
Subject: Re: [Rasch] Bunched versus spread out items to measure depression
To: "Bond,Trevor" <trevor.bond at jcu.edu.au>, "Bond,Trevor" <trevor.bond at jcu.edu.au>, "rasch" <rasch at acer.edu.au>
Cc: "Jose Alves" <alves at psi.uminho.pt>, "Jose Alves" <alves at iep.uminho.pt>
Date: Saturday, July 23, 2011, 6:25 AM

We had people with a very wide range of depression from none to a lot.  We had a sample from listservs for depressed people and regular depressed people.  It might be that depression is not Guttman like, i.e. one does not have to be a little sad before one cries a lot and skulks, and before one stops leaving ones room.  We found it was just about how many items with about the same Rasch score predicted the amount of depression.  Many of the common depression scales such as the Hamilton and Beck seem to have the same property when we Rasch analyzed them.''

MLC

-----Original Message-----
>From: "Bond, Trevor" <trevor.bond at jcu.edu.au>
>Sent: Jul 23, 2011 3:15 AM
>To: "Bond, Trevor" <trevor.bond at jcu.edu.au>, Michael Lamport Commons <commons at tiac.net>, rasch <rasch at acer.edu.au>
>Cc: Jose Alves <alves at psi.uminho.pt>, Jose Alves <alves at iep.uminho.pt>
>Subject: Re: [Rasch] Bunched versus spread out items to measure depression
>
>Ooops drinking champagne at breakfast time:
>Large person SE (sic.)= too few items. Or huge targetting problem
>
>
>On 23/07/11 8:39 AM, "Bond, Trevor" <trevor.bond at jcu.edu.au> wrote:
>
>> Large person SD = too few items.
>> Bunching items is useful if you have a high stakes cut-point to use.
>> Best
>> T
>> 
>> 
>> On 21/07/11 8:48 PM, "Michael Lamport Commons" <commons at tiac.net> wrote:
>> 
>>> Dear List Members:
>> 
>> What are the disadvantages and advantages of having the
>>> Rasch item scores bunched up with a small S.D. versus spread out for items to
>>> measure depression?  There person Rasch score have a very large S.D. which
>>> indicates that the items are capturing a wide range of depression
>> 
>> 
>> 
>> My
>>> Best,
>> 
>> Michael Lamport Commons, Ph.D.
>> Assistant Clinical Professor
>> 
>> Department
>>> of Psychiatry
>> Harvard Medical School
>> Beth Israel Deaconess Medical Center
>> 234
>>> Huron Avenue
>> Cambridge, MA 02138-1328
>> 
>> Telephone (617) 497-5270
>> Facsimile
>>> (617) 491-5270
>> Cellular (617)
>>> 320­0896
>> Commons at tiac.net
>> http://dareassociation.org/
>> ________________________
>>> _______________________
>> Rasch mailing list
>> Rasch at acer.edu.au
>> Unsubscribe:
>>> 
>https://mailinglist.acer.edu.au/mailman/options/rasch/trevor.bond%40jcu.edu.a>>
>u
>> 
>> 
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>
>


My Best,

Michael Lamport Commons, Ph.D.
Assistant Clinical Professor

Department of Psychiatry
Harvard Medical School
Beth Israel Deaconess Medical Center
234 Huron Avenue
Cambridge, MA 02138-1328

Telephone (617) 497-5270
Facsimile   (617) 491-5270
Cellular    (617) 320–0896
Commons at tiac.net
http://dareassociation.org/
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