[Rasch] formative v. reflective measures in assessment research

l.tesio at auxologico.it l.tesio at auxologico.it
Sun Oct 27 22:14:10 EST 2013

very good comments.
Luigi Tesio

Il 26/10/13 18:34, Thomas Salzberger ha scritto:
> Don & Luis,
> I fear Jack et al.'s paper on causal Rasch models is not exactly what 
> Don looks for. The idea of a Causal RM is that one should identify the 
> mechanism that drives measurement and experimentally manipulate item 
> difficulty and person ability.
> Formative "measurement", or "formative indicators",  is something 
> else. But Jack has also commented on this 
> (http://www.rasch.org/rmt/rmt221d.htm).
> It does not surprise me that many Rasch advocates know very little or 
> nothing about "formative measurement". And for a good reason.
> In my mind, formative measurement is a misconception, a fallacy (see 
> Edwards: The fallacy of formative measurement, Organizational Research 
> Methods 2011 vol. 14 no. 2 370-38), and seriously misleading.
> Borsboom (2003 The /Theoretical Status of Latent Variables/. Denny 
> Borsboom, Gideon J. Mellenbergh, and Jaap van Heerden in Psychological 
> Review; 2005 book Measuring the mind) has convincingly demonstrated 
> that the idea of a latent variable (and thus, a unidimensional 
> construct) and formative "measurement" are incompatible provided you 
> are in the realist camp.
> If you critically question Jarvis et al's rules for deciding whether 
> something has to be measured with reflective indicators (-> factor 
> analysis in CTT, IRT, Rasch) or formative indicators (-> ? what 
> "model" would you actually use?), then you notice that the criteria 
> follow from what you assume (reflective or formative) in the first 
> place. Yes, there sometimes is indeed a misspecification, but it is 
> not a misspecification in terms of reflective measurement vs formative 
> measurement. Rather, it is a misspecification with respect to 
> measurement vs the summary of measurements. The latter essentially is 
> a structural model.
> The reason why many people have no problems accepting formative 
> measurement as measurement is probably due to Stevens' definition of 
> measurement. If assigning numerals and interpreting them as numbers is 
> measurement, then of course formative indicators also give you 
> measurement. But then anything goes.
> I was contacted by my agent to make changes in my policy
> I was contacted by my agent to sell me more life insurance
> I was contacted by my agent to describe new insurance offerings
> I was contacted by my agent to keep my policy in place
> This does not make any sense to me. If you are interested in the 
> intensity of contact, why not just ask whether one was contacted?
> You may add reasons and that gives you additional information. But 
> these items do not form a scale, and the sum score cannot lead to 
> measurement.
> If I wanted to measure "subjective warmth", I would not use the 
> following items, would I:
> I feel warm because it is hot outside.
> I feel warm because the heating is on.
> I feel warm because I have a fever.
> Best
> Thomas
> 2013/10/26 Luis Carlos Orozco <lcorovar at gmail.com 
> <mailto:lcorovar at gmail.com>>
>     There is a recent article in Frontiers in Psychology august 2013
>     volume 4 by Stenner, Fisher, Stone , Burdick  "Causal Rasch
>     models". That could help you.
>     Luis C. Orozco V. MD MSc
>     Profesor Asociado
>     Escuela de Enfermería
>     Universidad Industrial de Santander
>     Colombia
>     2013/10/26 Donald Bacon <dbacon at du.edu <mailto:dbacon at du.edu>>
>         Hi all --
>         To offer more explanation on my reflective v. formative
>         question, in reflective measurement models, the
>         construct/latent trait causes the measures/indicators/items,
>         whereas in formative models, the measures cause the latent
>         trait. Jarvis, MacKenzie and Podsakoff (J Consumer Research,
>         2003) offer a thorough description of this difference. They
>         cite Bollen and Lennox (Psych Bull, 1991) as identifying the
>         same distinction, except that Bollen and Lennox call
>         reflective indicators 'effects indicators' in a principal
>         component model, and formative indicators 'causal indicators'
>         in a composite latent construct model.
>         Jarvis et al. cite a formative example from Crosby and
>         Stephens (1987) that I will paraphrase here. In measuring the
>         construct "personal contact with life insurance agents",
>         suppose the following measures are used:
>         I was contacted by my agent to make changes in my policy
>         I was contacted by my agent to sell me more life insurance
>         I was contacted by my agent to describe new insurance offerings
>         I was contacted by my agent to keep my policy in place
>         In these items, the agent would not suggest keeping the policy
>         and changing the policy, so the inter-item correlations here
>         should be low or perhaps even negative, yet all of these
>         statements indicate personal contact.  Internal consistency is
>         not necessary for formative measures; to assess the quality of
>         formative measures we need to look at criterion-related
>         validity.  Thus, formative models are a bit more like
>         regression models, where the many independent variables are
>         assumed to have no error and may have low intercorrrelations
>         but the one dependent variable does have error.
>         Jarvis et al. go on to report how measurement models have
>         often been misspecified, even in top marketing journals, as
>         formative measures have been treated as reflective and vice
>         versa.  They show how such misspecification can bias
>         structural path estimates.
>         Getting back to Rasch measurement, it seems to me that Rasch
>         assumes a reflective/effects/principal components model.
>         However, Rasch may occasionally be misapplied to formative
>         indicators.  In the latter case, model fit and internal
>         consistency would probably be low, but this is due mainly to
>         fundamental model misspecification. Or can Rasch be used with
>         formative indicators?
>         Has this type of model misspecification been discussed in the
>         Rasch literature?  More specifically, are all tests of ability
>         or knowledge generally reflective models?  Is there a good
>         cite that someone can point me too?
>         Thanks for any insights you may be able to provide.
>         Don
>         *From:*rasch-bounces at acer.edu.au
>         <mailto:rasch-bounces at acer.edu.au>
>         [mailto:rasch-bounces at acer.edu.au
>         <mailto:rasch-bounces at acer.edu.au>] *On Behalf Of *Bond, Trevor
>         *Sent:* Saturday, October 26, 2013 1:17 AM
>         *To:* rasch at acer.edu.au <mailto:rasch at acer.edu.au>
>         *Subject:* Re: [Rasch] formative v. reflective measures in
>         assessment research
>         Dear Donald,
>         Perhaps you could share what you mean by formative and
>         reflective, so we might be able better to answer your question.
>         Collegially
>         TGB
>         *From: *Donald Bacon <dbacon at du.edu <mailto:dbacon at du.edu>>
>         *Reply-To: *"rasch at acer.edu.au <mailto:rasch at acer.edu.au>"
>         <rasch at acer.edu.au <mailto:rasch at acer.edu.au>>
>         *Date: *Saturday, 26 October 2013 3:57 AM
>         *To: *"rasch at acer.edu.au <mailto:rasch at acer.edu.au>"
>         <rasch at acer.edu.au <mailto:rasch at acer.edu.au>>
>         *Subject: *[Rasch] formative v. reflective measures in
>         assessment research
>         Hi all --
>         The Rasch model assumes that each measure in a scale reflects
>         the same underlying trait, and so it seems that a reflective
>         measurement model is appropriate, and internal consistency is
>         a desirable quality.  But what about the case of a long
>         comprehensive exam, such as one we might use for assessment.
>         In my experience, these exams often behave as if they were
>         close to unidimensional, even though many different learning
>         outcomes are captured.  If well designed, these tests often
>         exhibit high internal consistency.  Because the models fit
>         well, I've always thought of the measures as reflective, but
>         perhaps my theory is wrong even though the fit is good; maybe
>         the measures are formative.  Is there any way to use the Rasch
>         model with formative indicators?
>         Thanks for any insights you might have --
>         Don
>         Donald R. Bacon, Ph.D.
>         Professor of Marketing
>         Editor, Journal of Marketing Education
>         Daniels College of Business
>         University of Denver
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> -- 
> ___________________________________
> Thomas.Salzberger at gmail.com <mailto:Thomas.Salzberger at gmail.com>
> Thomas.Salzberger at wu.ac.at <mailto:Thomas.Salzberger at wu.ac.at>
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Luigi Tesio, Professore Ordinario
Cattedra di Medicina Fisica e Riabilitativa
Università degli Studi di Milano
Unità Clinica e Laboratorio di Ricerche di Riabilitazione Neuromotoria
Ospedale San Luca, Istituto Auxologico Italiano-IRCCS
via Mercalli,32
20122 Milano, Italy
tel +390258218154
fax +390259218152
e.mail : luigi.tesio at unimi.it
e-mail : l.tesio at auxologico.it

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