References of "Magis, David"
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See detailOn the relationships between Jeffreys modal and weighted likelihood estimation of ability under logistic IRT models
Magis, David ULg; Raîche, Gilles

in Psychometrika (2012), 77

This paper focuses on two estimators of ability with logistic item response theory models: the Bayesian modal (BM) estimator and the weighted likelihood (WL) estimator. For the BM estimator, Jeffreys’ ... [more ▼]

This paper focuses on two estimators of ability with logistic item response theory models: the Bayesian modal (BM) estimator and the weighted likelihood (WL) estimator. For the BM estimator, Jeffreys’ prior distribution is considered, and the corresponding estimator is referred to as the Jeffreys modal (JM) estimator. It is established that under the three-parameter logistic model, the JM estimator returns larger estimates than the WL estimator. Several implications of this result are outlined. [less ▲]

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See detailOn the difficulty of relational concepts among participants with Down syndrome
Facon, Bruno; Magis, David ULg; Courbois, Yannick

in Research in Developmental Disabilities (2012), 33

The aim of the study was to compare the difficulty of relational concepts among participants with and without intellectual disability. The French versions of the Boehm Tests of Basic Concepts Third ... [more ▼]

The aim of the study was to compare the difficulty of relational concepts among participants with and without intellectual disability. The French versions of the Boehm Tests of Basic Concepts Third Edition (Preschool and Kindergarten to 2nd grade) were administered to three groups of 47 participants individually matched on their total raw score on the tests. The first group comprised participants with intellectual disability of undifferentiated etiology, the second, participants with Down syndrome and the third, typical children. Item analyses using the transformed item difficulties method to detect differential item functioning across groups showed that the groups' rank-orders of item difficulty were highly similar. It is concluded that, all things being equal, relational concepts are of comparable difficulty and follow a similar sequence of development whatever the cognitive and etiological status of participants. Methodological and theoretical implications of these findings are discussed. [less ▲]

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See detailA modified item response model to detect and correct for cheating
Magis, David ULg; Raîche, Gilles

Conference (2011, October 13)

This talk focuses on the identification of respondents with cheating behaviour to educational or psychometric tests. Cheating behaviour is often observed when some examinee with low ability level, tries ... [more ▼]

This talk focuses on the identification of respondents with cheating behaviour to educational or psychometric tests. Cheating behaviour is often observed when some examinee with low ability level, tries to get correct responses (in some way or another) to get higher grades. This results usually in a response pattern that does not fit the underlying item response theory (IRT) model and severely affects the estimation of ability level. Until now, several indices of misfit have been proposed, and they seem accurate for detecting cheating (as well as other misfitting behaviours). Unfortunately, none of these indexes permit: (a) to determine which type of behaviour is encountered, and (b) to propose a corrected estimation of the examinee’s ability level. The purpose of this talk is to present Raîche’s multidimensional model as an extension of the usual IRT models but incorporating additional person parameters to characterize misfitting behaviour. Emphasis is put on a simple model with personal pseudo-guessing variation to detect trends in cheating. Results from a simulation study indicate that, in the absence of cheating, the multidimensional model returns similar estimates than the traditional IRT models, while in the presence of cheating, the person pseudo-guessing parameter is an accurate index of misfit and the person ability estimates are less biased than its traditional counterpart. [less ▲]

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See detailRobust DIF analysis
Magis, David ULg

Conference (2011, October 11)

This talk focuses on the issue of differential item functioning in psychometrics. An item is said to function differently if examinees from different groups, but with the same ability levels, have ... [more ▼]

This talk focuses on the issue of differential item functioning in psychometrics. An item is said to function differently if examinees from different groups, but with the same ability levels, have nevertheless different probabilities of endorsing this item. Many methods were proposed to detect DIF, either based on statistical methods (such as logistic regression) or on IRT models. The talk is divided into three parts. In the first part, a brief overview of the DIF framework and methods is proposed. In the second part, a recent, conceptually different approach to DIF will be introduced. It consists basically in flagging as DIF, the items that are outlying withb respect to other items. This approach is based on robust statistical tools for outlier identification. It cancels the issue of Type I error inflation and the need for purification of the anchor set. In the third part, it is briefly outlined how this approach easily extends to the simultaneous comparison of more than two groups of examinees; multivariate robust estimators of location and scale are required, but their use might overcome the standard methods for simultaneous pairwise comparisons. [less ▲]

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See detailBasic use and programming in the R language
Magis, David ULg

Scientific conference (2011, August 22)

R is an open-source statistical software and of increasing interest for the scientific community. It can be installed on all usual platforms (Windows, Linux, Mac) and is suitable for many statistical ... [more ▼]

R is an open-source statistical software and of increasing interest for the scientific community. It can be installed on all usual platforms (Windows, Linux, Mac) and is suitable for many statistical analyzes, graphical representation, intensive computation and programming, among others. New functionalities and packages are developed regularly and the R web community ensures a constant development and increasing usefulness of R, not only for pure statisticians but also for practitioners from various fields (psychology, education, biometrics, econometrics, etc.). Its main drawback, however, is that it requires preliminary training and practice to handle the various aspects of the software and to become efficient in using R. The purpose of this workshop is to present the basic aspects of R, from the installation to the basic statistical analysis. The following themes will be developed: installation, importing data, R objects and structures, basic computations, graphics, packages and libraries, programming in R, basic statistical modeling and testing. The workshop will be practice-oriented, with sessions mixing both “theoretical” presentations and practical applications. Live demonstrations of R will also be performed. Participants are invited to bring their laptop and to take part to the practical exercises. Slides, R scripts and illustrative data sets will be provided. [less ▲]

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See detailA Bayesian person fit evaluation for polytomous response data
Béland, Sébastien; Hoijtink, Herbert; Raîche, Gilles et al

Conference (2011, July 19)

Studies about Person-fit are generally produced under a frequentist approach. For example, Meijer & Sijtsma (2001) discussed many parametric and non-parametric indexes in their review on this topic ... [more ▼]

Studies about Person-fit are generally produced under a frequentist approach. For example, Meijer & Sijtsma (2001) discussed many parametric and non-parametric indexes in their review on this topic. However, it exists also few papers about the investigation of person-fit in a Bayesian context (e.g. Glas & Meijer, 2003; Van Der Linden & Guo, 2008). In this talk, we present a new method based on the evaluation of informative hypotheses using the Bayes factor. This approach is non-parametric in nature and can be applied to a large variety of situations and many types of data. Here, we focus on the use of Bayesian person-fit methods that can be used with polytomous response data. This presentation is divided in two sections. First, we present the technical aspects of this approach by discussing some hypotheses of interest, the nature of the prior and the nature of the posterior. Second, we present results from a real data matrix. The first analysis shows that Bayesian person-fit evaluation is efficient and can be easily applied to small data matrices. [less ▲]

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See detailApplication de l’indice Lz pour l’élimination de données de recherche en langues
Pichette, François; Béland, Sébastien; Raîche, Gilles et al

Conference (2011, May 10)

L’indice de détection de patrons de réponses inappropriés Lz (Drasgow, Levine et Williams, 1985) a été appliqué à un test d’habileté en lecture en langue seconde de 64 items (Pichette, 2008) mené auprès ... [more ▼]

L’indice de détection de patrons de réponses inappropriés Lz (Drasgow, Levine et Williams, 1985) a été appliqué à un test d’habileté en lecture en langue seconde de 64 items (Pichette, 2008) mené auprès de 171 étudiants universitaires. L’objectif principal de cette recherche est d’exclure les participants au profil de réponses aberrant. Des coefficients de validité et de fiabilité sont comparés entre les données éliminées sur la base de l’intuition des chercheurs et les éliminations suggérées par l’indice Lz. Cette approche permet de détecter des participants additionnels dont le patron de réponses est non représentatif de l’habileté qu’on désire mesurer. [less ▲]

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See detailEtude comparative de l'indice Lz dans le cadre de données dichotomique et de données polytomique
Béland, Sébastien; Raîche, Gilles; Magis, David ULg et al

Conference (2011, May 10)

L’indice de détection de patrons de réponses inappropriés Lz (Drasgow, Levine et Williams, 1985) est fort probablement l’indice le plus connu et le plus utilisé par les patriciens et les chercheurs en ... [more ▼]

L’indice de détection de patrons de réponses inappropriés Lz (Drasgow, Levine et Williams, 1985) est fort probablement l’indice le plus connu et le plus utilisé par les patriciens et les chercheurs en mesure. Ainsi, on a surtout étudié le comportement de Lz lorsqu’il est utilisé avec des données dichotomique mais il est aussi possible de l’analyser avec des données polytomique. Dans le cadre de cette recherche, nous proposons de comparer les résultats des indices Lz dichotomique et Lz polytomique. Pour ce faire, (i) nous utiliserons l’indice Kappa de Cohen pour comparer si les patrons de réponses détectés entre les deux versions de l’indice sont les mêmes et (ii) nous étudierons leur distribution respectives. [less ▲]

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See detailRecent R packages in psychometrics
Béland, Sébastien; Raîche, Gilles; Magis, David ULg

Scientific conference (2011, April 06)

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See detailThe difR package, a toolbox for the identification dichotomous differential item functioning
Magis, David ULg

Conference (2011, February 25)

The purpose of this talk is to briefly introduce the R package difR to identify differential item functioning (DIF) among dichotomously scored items. The presentation is organized in three points. First ... [more ▼]

The purpose of this talk is to briefly introduce the R package difR to identify differential item functioning (DIF) among dichotomously scored items. The presentation is organized in three points. First, the general framework of DIF is outlined and the most known methods are presented succinctly. Second, the main functionalities of the difR package are described. Third, a practical application of difR is performed by a “live” analysis of a real example with several DIF methods. Future developments and objectives are discussed to conclude the talk. The difR package was jointly developed by Sébastien Béland (Université du Québec à Montréal, Canada), Francis Tuerlinckx (K. U. Leuven, Belgium) and Paul De Boeck (University of Amsterdam, The Netherlands). [less ▲]

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See detailUne solution numérique au test de Cattell pour déterminer le nombre de composantes principales à retenir
Raîche, Gilles; Magis, David ULg; Walls, Theodore et al

in Raîche, Gilles; Paquette-Côté, Karine; Magis, David (Eds.) Des mécanismes pour assurer la validité de l’interprétation de la mesure en éducation. Tome 1 : la mesure. (2011)

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See detailIdentification of differential item functioning in multiple-group settings: A multivariate outlier detection approach
Magis, David ULg; De Boeck, Paul

in Multivariate Behavioral Research (2011), 46

This paper focuses on the identification of differential item functioning (DIF) when more than two groups of examinees are considered. We propose to consider items as elements of a multivariate space ... [more ▼]

This paper focuses on the identification of differential item functioning (DIF) when more than two groups of examinees are considered. We propose to consider items as elements of a multivariate space, where DIF items are outlying elements. Following this approach, the situation of multiple groups is a quite natural case. A robust statistics technique is proposed to identify DIF items as outliers in the multivariate space. For low dimensionalities, up to two three groups, also a simple graphical tool is derived. We illustrate our approach with a re-analysis of data from Kim, Cohen, and Park (1995) on using calculators for a mathematics test. [less ▲]

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See detailA generalized logistic regression procedure to detect differential item functioning among multiple groups
Magis, David ULg; Raîche, Gilles; Béland, Sébastien et al

in International Journal of Testing (2011), 11

We present an extension of the logistic regression procedure to identify dichotomous differential item functioning (DIF) in the presence of more than two groups of respondents. Starting from the usual ... [more ▼]

We present an extension of the logistic regression procedure to identify dichotomous differential item functioning (DIF) in the presence of more than two groups of respondents. Starting from the usual framework of a single focal group, we propose a general approach to estimate the item response functions in each group and to test for the presence of uniform DIF, non uniform DIF, or both. This generalized procedure is compared to other existing DIF methods for multiple groups with a real data set on language skill assessment. Emphasis is put on the flexibility, completeness and computational easiness of the generalized method. [less ▲]

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See detailBeyond matching on the mean in developmental disabilities research
Facon, Bruno; Magis, David ULg; Belmont, John M

in Research in Developmental Disabilities (2011), 32

The matching of groups is a traditional way to control for confounding variables in developmental disability research. The equivalency of means across groups is routinely checked for these variables, but ... [more ▼]

The matching of groups is a traditional way to control for confounding variables in developmental disability research. The equivalency of means across groups is routinely checked for these variables, but not the homogeneity of their variances or the shapes of their distributions. In the present paper, it is argued that group matching can go seriously wrong unless it directly confronts the distributional concerns by the use of well-known statistical indices and very simple graphical displays of the distributions. The question of the equivalency of item response profiles is also addressed since two participants or two groups of participants can obtain the same overall score on the matching variable by passing different items. In this case, the matching cannot be considered satisfactory because of poor concordance between the molar (overall score) and molecular (item scores) levels of matching. Angoff's Delta plot method, a statistical approach for detecting differential item functioning across small groups is described. It is promising as a simple way to prove whole test/individual item correspondence and, in addition, a useful tool for making post-hoc statistical analyses at the item level on the dependant variables. [less ▲]

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See detailcatR: an R package for computerized adaptive testing
Magis, David ULg; Raîche, Gilles

in Applied Psychological Measurement (2011), 35

Computerized adaptive testing (CAT) is an active current research field in psychometrics and educational measurement. However, there is very little software available to handle such adaptive tasks. The R ... [more ▼]

Computerized adaptive testing (CAT) is an active current research field in psychometrics and educational measurement. However, there is very little software available to handle such adaptive tasks. The R package catR was developed to perform adaptive testing with as much flexibility as possible, in an attempt to provide a developmental and testing platform to the interested user. Several item-selection rules and ability estimators are implemented. The item bank can be provided by the user or randomly generated from parent distributions of item parameters. Three stopping rules are available. The output can be graphically displayed. [less ▲]

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See detailDes mécanismes pour assurer la validité de l’interprétation de la mesure en éducation. Tome 2: l'évaluation.
Raîche, Gilles; Paquette-Côté, Karine; Magis, David ULg

Book published by Presses de l'Université du Québec (2011)

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See detailDes mécanismes pour assurer la validité de l’interprétation de la mesure en éducation. Tome 1 : la mesure.
Raîche, Gilles; Paquette-Côté, Karine; Magis, David ULg

Book published by Presses de l'Université du Québec (2011)

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See detailComparaison empirique des méthodes classiques de détection du fonctionnement différentiel d’items en psychométrie
Magis, David ULg; De Boeck, Paul; Raîche, Gilles

in Raîche, Gilles; Paquette-Côté, Karine; Magis, David (Eds.) Des mécanismes pour assurer la validité de l’interprétation de la mesure en éducation. Tome 1 : la mesure. (2011)

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See detailPour assurer la validité de l'interprétation de la mesure en éducation: aspects pratiques
Magis, David ULg; Raîche, Gilles; Paquette-Côté, Karine

in Raîche, Gilles; Paquette-Côté, Karine; Magis, David (Eds.) Des mécanismes pour assurer la validité de l'interprétation de la mesure en éducation. Tome 2: l'évaluation. (2011)

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See detailÉtude du fonctionnement différentiel d'item dans le cadre du test de classement en anglais-langue seconde (TCALS-II)
Béland, Sébastien; Magis, David ULg; Raîche, Gilles

in Blais, Jean-Guy; Gilles, Jean-Luc (Eds.) Evaluation des apprentissages et technologies de l'information et de la communication : Le futur est à notre porte (2011)

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