Search results for "Latent trait"
showing 6 items of 6 documents
Variational Approximations for Generalized Linear Latent Variable Models
2017
Generalized linear latent variable models (GLLVMs) are a powerful class of models for understanding the relationships among multiple, correlated responses. Estimation, however, presents a major challenge, as the marginal likelihood does not possess a closed form for nonnormal responses. We propose a variational approximation (VA) method for estimating GLLVMs. For the common cases of binary, ordinal, and overdispersed count data, we derive fully closed-form approximations to the marginal log-likelihood function in each case. Compared to other methods such as the expectation-maximization algorithm, estimation using VA is fast and straightforward to implement. Predictions of the latent variabl…
A polydiagnostic scale for dimensional classification of endogenous depression. Derivation and validation.
1986
Several operational diagnoses (OPD) for endogenous depression have been proposed. However--though aiming at similar clinical concepts--the amount of association and agreement between different OPD is rather low. In this study the relationship between eight OPD (Research Diagnostic Criteria, DSM-III, Michigan Discrimination Index, Newcastle Scale I, Newcastle Scale II, Taylor-Abrams Criteria, Vienna Research Criteria, Hamilton Endogenomorphy Index) was assessed by applying latent trait analyses to the classificatory data of these eight OPD which were rated simultaneously in a sample of 173 depressive inpatients. According to these analyses six OPD (RDC, DSM-III, NCS-I, NCS-II, TAC and VRC) a…
Building up adjusted indicators of students' evaluation of university courses using generalized item response models
2012
This article advances a proposal for building up adjusted composite indicators of the quality of university courses from students’ assessments. The flexible framework of Generalized Item Response Models is adopted here for controlling the sources of heterogeneity in the data structure that make evaluations across courses not directly comparable. Specifically, it allows us to: jointly model students’ ratings to the set of items which define the quality of university courses; explicitly consider the dimensionality of the items composing the evaluation form; evaluate and remove the effect of potential confounding factors which may affect students’ evaluation; model the intra-cluster variabilit…
Flexible latent trait aggregation to analyze employability after the Ph.D. in Italy
2015
The analysis of satisfaction, employability and economic perspectives after the Ph.D. in Italy has not received adequate attention in the past, especially in terms of comparison among universities. To analyze these aspects, in this paper we consider data from the survey ‘Statistica in TEma di Laureati e LAvoro’ on doctors who achieved the title on 2007, 2008 and 2009 [CILEA, Laureati STELLA, indagine occupazionale post-dottorato, dottori di ricerca 2007–2008, Tech. Rep., CILEA, Segrate, 2010; CILEA,Laureati STELLA, indagine occupazionale post-dottorato, dottori di ricerca 2008–2009, Tech. Rep., CILEA, Segrate, 2011]. To deal with the complex, multidimensional nature of the concept, we propo…
Psychometric Properties of the Scoliosis Research Society Questionnaire (Version 22r) Domains Among Adults With Spinal Deformity : A Rasch Measuremen…
2022
Objective: Adults with degenerative spinal deformity (ASD) have lower health-related quality of life (HRQL) compared to the general population. Applying Rasch Measurement Theory (RMT), this study tested the revised Scoliosis Research Society-22 (SRS-22r) HRQL instrument among symptomatic adult patients with degenerative spinal disorders and varying degrees of ASD. Methods: SRS-22r data from 637 outpatient spine clinic patients with degenerative spine conditions were investigated for unidimensionality, item/scale fit, differential item functioning (DIF), scale coverage/targeting, and person separation index (PSI) using RMT. Results: Unidimensionality of the SRS-22r was not supported for eith…
Measuring Vulnerability of Asylum Seekers and Refugees in Italy
2019
In recent years, a growing number of forced migrants have travelled to Italy across the Mediterranean Sea. While the number of new arrivals has diminished since 2017, the Italian reception system still struggles to process the high number of applications for international protection. A significant proportion of forced migrants who arrive in Italy end up living in informal settlements, such as occupied buildings, shacks, containers and tented camps. In this study, we assess the vulnerability of asylum seekers and refugees living in informal settlements in Italy, using data from the first nationally representative survey of this population. We compare a count measure of vulnerability with a n…