[Rasch] Bunched versus spread out items to measure depression

Paul Barrett paul at pbarrett.net
Sun Jul 24 14:19:37 EST 2011


I’m curious about how many seem to be  understanding ‘Depression’, with
relevance to an individual who is very (clinically) depressed (showing
physiological/chronometric/attentional deficits, hippocampal neurogenesis
attenuation, as well as affective disturbances) and someone who just feels a
bit ‘down’. 

 

To assume that the ‘state of ’ depression varies additively, with
equal-interval ‘units of depression’ forming linear magnitudes of affect, is
a huge assumption, which needs empirical and experimental justification. The
fit or otherwise of the Rasch model to a set of self-report item responses
is not the same as stating that something which might be called “Depression”
varies additively. That latter statement  requires a different kind of
empirical evidence altogether.

 

Anyway, for a very nice discussion concerning the Beck,  and the concept of
Depression as a ‘variable’, try Hammond, S.M. (1995) An IRT investigation of
the validity of non-patient analogue research using the Beck Depression
Inventory. European Journal of Psychological Assessment, 11, 1, 14-20.

Abstract

This paper presents an IRT analysis of the Beck Depression Inventory which
was carried out to assess the assumption of an underlying latent trait
common to non-clinical and patient samples. A one parameter rating scale
model was fitted to data drawn from a patient and non-patient sample.
Findings suggest that while the BDI fits the model reasonably well for the
two samples separately there is sufficient differential item functioning to
raise serious doubts of the viability of using it analogously with patient
and non-patient groups.  

 

Regards .. Paul

 

Advanced Projects R&D Ltd.

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From: rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au] On Behalf
Of Rense Lange
Sent: Sunday, 24 July 2011 1:44 p.m.
To: Ian Wilson
Cc: Rasch
Subject: Re: [Rasch] Bunched versus spread out items to measure depression

 

This is not to defend the Beck, but I must disagree in general. The Rasch
measure defined by the Beck raw scores (provided the items fit the model,
etc) IS a quantitative variable. I grant you, there are only n+1 (where n =
# questions) point that are defined. When the same no of questions are used,
questionnaires using rating scales differ wrt the number of defined points
on the Rasch dimension, true enough. But, there is no inherent qualitative
difference, just one of resolution / granularity. Add more dichotomous
questions to the Beck, and you can have the same resolution (at least
locally) as any rating scale based measure. Caveat: It is difficult to say
beforehand how many dichotomous questions should be added to achieve
equivalence, as this depends on what is meant by resolution, equivalence,
item properties, # categories, etc.

 

Rense Lange

 

 

On Jul 23, 2011, at 8:15 PM, Ian Wilson wrote:





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

 

 

 

 

 



 

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C.P. 78216 MEXICO

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--- 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
<http://us.mc1115.mail.yahoo.com/mc/compose?to=trevor.bond@jcu.edu.au> >
>Sent: Jul 23, 2011 3:15 AM
>To: "Bond, Trevor" <trevor.bond at jcu.edu.au
<http://us.mc1115.mail.yahoo.com/mc/compose?to=trevor.bond@jcu.edu.au> >,
Michael Lamport Commons <commons at tiac.net
<http://us.mc1115.mail.yahoo.com/mc/compose?to=commons@tiac.net> >, rasch
<rasch at acer.edu.au
<http://us.mc1115.mail.yahoo.com/mc/compose?to=rasch@acer.edu.au> >
>Cc: Jose Alves <alves at psi.uminho.pt
<http://us.mc1115.mail.yahoo.com/mc/compose?to=alves@psi.uminho.pt> >, Jose
Alves <alves at iep.uminho.pt
<http://us.mc1115.mail.yahoo.com/mc/compose?to=alves@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
<http://us.mc1115.mail.yahoo.com/mc/compose?to=trevor.bond@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
<http://us.mc1115.mail.yahoo.com/mc/compose?to=commons@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://us.mc1115.mail.yahoo.com/mc/compose?to=Commons@tiac.net> 
>> http://dareassociation.org/
>> ________________________
>>> _______________________
>> Rasch mailing list
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>> 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://us.mc1115.mail.yahoo.com/mc/compose?to=Commons@tiac.net> 
http://dareassociation.org/
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