ltm : An R Package for Latent Variable Modeling and Item Response Theory Analyses

Journal of statistical software (Impact Factor: 3.8). 01/2006; 17(5). DOI: 10.18637/jss.v017.i05

ABSTRACT The R package ltm has been developed for the analysis of multivariate dichotomous and polytomous data using latent variable models, under the Item Response Theory ap-proach. For dichotomous data the Rasch, the Two-Parameter Logistic, and Birnbaum's Three-Parameter models have been implemented, whereas for polytomous data Seme-jima's Graded Response model is available. Parameter estimates are obtained under marginal maximum likelihood using the Gauss-Hermite quadrature rule. The capabilities and features of the package are illustrated using two real data examples.

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    • "Questionnaire items of externalizing problems were analyzed with graded response models in IRT (Samejima, 1969) using the ltm package (Rizopoulos, 2006) in R 3.0 (R "
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    ABSTRACT: The present study applied item response theory to identify an efficient set of items of the Achenbach Externalizing scale from the Child Behavior Checklist (CBCL; 33 items) and Teacher's Report Form (TRF; 35 items) that were sensitive to clinical-range scores. Mothers and teachers rated children's externalizing problems annually from ages 5 to 13 years in 2 independent samples (Ns = 585 and 1,199). Item properties for each rater across ages 5-8 and 9-13 were examined with item response theory. We identified 10 mother- and teacher-reported items from both samples based on the items' measurement precision for subclinical and clinical levels of externalizing problems: externalizing problems that involve meanness to others, destroying others' things, fighting, lying and cheating, attacking people, screaming, swearing/obscene language, temper tantrums, threatening people, and being loud. Scores on the scales using these items had strong reliability and psychometric properties, capturing nearly as much information as the full Externalizing scale for classifying clinical levels of externalizing problems. Scores on the scale with the 10 CBCL items had moderate accuracy, equivalent to the full Externalizing scale, in classifying diagnoses of conduct disorder based on a research diagnostic interview. Of course, comprehensive clinical assessment would consider additional items, dimensions of behavior, and sources of information, too, but it appears that the behaviors tapped by this select set of items may be core to externalizing psychopathology in children. (PsycINFO Database Record (c) 2015 APA, all rights reserved).
    Psychological Assessment 08/2015; DOI:10.1037/pas0000185 · 2.99 Impact Factor
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    • "The fixed amount forced the decision makers to allocate the points to the investment categories they believed to be the most ben - eficial contingent upon their decision scenarios . To derive sensible scores from the present scales ' ordinal items , a gener - alised partial credit model ( Muraki 1992 ) was estimated using the package ' ltm ' in R ( Rizopoulos 2006 ) . Managers ' scores were computed using expected a posteriori ( EAP ) estimates and subsequently rescaled to an interval from 0 to 10 to ease interpretation ( for the transformation , extreme values were determined by EAP estimates of observations scoring either in the lowest or highest categories for all items ) . "
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    ABSTRACT: Green investments are crucial mechanisms for translating green operation strategies into managerial action. We examine the impact of external pressures on green investment patterns in terms of their scope, type and time horizon across 251 German and US managers. A scenario-based experiment was conducted using a 2 × 2 × 2 factorial design in which managers were assigned to high and low consumer, community, and resource treatment groups before being asked to make green investment decisions. Our hypotheses are developed based on resource advantage theory and tested in a number of regression models. The results demonstrate that German and US managers respond differently to external pressures in their green investment decisions. Regarding the scope of green investments, German and US managers invest differently if end consumer pressure increases and partially differently if resource scarcity increases, but they act in a similar way if community pressure increases. Moreover, we detected specific variations in the type and time horizon of green investments across US and German managers. The theoretical and practical implications of these findings for green operations management research and for firms operating in multinational settings are explained.
    International Journal of Production Research 06/2015; 53(20). DOI:10.1080/00207543.2015.1047979 · 1.48 Impact Factor
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    • "The afore mentioned elements enable to contrast the model constructed a priori, establishing the whole set of relations between elements that form it, to give greater flexibility to the researcher in establishing a hypothesis about the construct structure (Bentler, 2007). Therefore, it is a kind of inferential analysis that uses multivariate regression to relate patterns of responses to a set of latent factors not directly observed, but according to the Substantive Theory (Rizopoulos, 2006) that exist in continuous dimensions of the people evaluated. This Structural Equation Model provides some technical procedures and criteria for validation of measurement models under two conditions (González-Montesinos & Backhoff, 2010): • Conditional independence, understood as a set of latent factors. "
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    ABSTRACT: This research includes the design of a questionnaire for evaluating cultural coexistence in secondary education classrooms (Berrocal, Olmedo & Olmos, 2014; Olmedo et al., 2014), as well as the comparison of its psychometric properties in a multicultural population of schools in southern Spain. An attempt is made to create a valid, reliable and useful tool for teachers to measure conflict situations in the classroom, as well as understanding the nature of the conflict from the point of view of all those involved. The metric aspects show a maximized content and construct validity (Muñiz, 2010) using a Structural Equation Model (SEM) and Confirmatory Factor Analysis (CFA) analysis, checking and modifying its model by Wald and Lagrange indicators (Bentler, 2007), to obtain the most adjusted model to the theoretical and goodness criteria.
    Suma Psicologica 12/2014; 221(2):107. DOI:10.1016/S0121-4381(14)70013-X
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