1,721,036 research outputs found
Item Response Theory Analysis of the Life Orientation Test-Revised: Age and Gender Differential Item Functioning Analyses
No full textThis study is aimed at testing the measurement properties of the Life Orientation Test-Revised (LOT-R) for the assessment of dispositional optimism by employing item response theory (IRT) analyses. The LOT-R was administered to a large sample of 2,862 Italian adults. First, confirmatory factor analyses demonstrated the theoretical conceptualization of the construct measured by the LOT-R as a single bipolar dimension. Subsequently, IRT analyses for polytomous, ordered response category data were applied to investigate the items’ properties. The equivalence of the items across gender and age was assessed by analyzing differential item functioning. Discrimination and severity parameters indicated that all items were able to distinguish people with different levels of optimism and adequately covered the spectrum of the latent trait. Additionally, the LOT-R appears to be gender invariant and, with minor exceptions, age invariant. Results provided evidence that the LOT-R is a reliable and valid measure of dispositional optimism
Ansia nei confronti della statistica e stile cognitivo: un'indagine sugli studenti di psicologia
No full text
Using Item Response Theory to Explore the Psychometric Properties of the Italian Version of the Child and Adolescent Mindfulness Measure (CAMM)
No full textThe Child and Adolescent Mindfulness Measure (CAMM) was specifically developed to assess mindfulness in children and adolescents. This study’s main aim was to explore the psychometric properties of the Italian version of the CAMM using item response theory (IRT). We investigated how well each item of the CAMM concurred in measuring mindfulness in children and adolescents, the reliability of the scale in measuring different levels of a trait, and whether items showed gender and age differential item functioning (DIF). The scale’s validity was tested by investigating the relationships of CAMM scores with emotion regulation, life satisfaction, and attention and depression problems. Our results confirmed the unidimensional structure of the scale and generated evidence that with a few exceptions, the items were able to discriminate well among respondents with different levels of the trait being measured and adequately covered the spectrum of the latent trait. Satisfactory information values were obtained for a substantial range of the trait, indicating that the Italian version of the CAMM is adequately reliable across the continuum of the trait. The entire scale appeared to be gender and age invariant and evidence of validity was provided. Using IRT, the current study provides information about the psychometric adequacy of the Italian version of the CAMM in measuring mindfulness in young people
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Fatigue investigation at high load ratio R of a quenched and tempered chromium molybdenum steel
Full text linkThe fatigue behavior at high number of cycles in elastic-plastic field of quenched and tempered carbon chromium steel was experimentally investigated for high performance reciprocating compressors application. Fatigue tests on un-notched specimens were performed both under load and strain controls, by imposing different levels of stress/strain and for each of them different values of stress ratios R, especially high values. Stress and strain trends have been monitored, during the fatigue life, and either ratcheting or relaxation, respectively, was evident. The stress control tests have resulted into fatigue fractures only for low values of R with significant ratcheting and an increasing rate during the final part of the test, thus the fracture could be considered as a synergy The fatigue behavior at high number of cycles in elastic-plastic field of quenched and tempered carbon chromium steel was experimentally investigated for high performance reciprocating compressors application. Fatigue tests on un-notched specimens were performed both under load and strain controls, by imposing different levels of stress/strain and for each of them different values of stress ratios R, especially high values. Stress and strain trends have been monitored, during the fatigue life, and either ratcheting or relaxation, respectively, was evident. The stress control tests have resulted into fatigue fractures only for low values of R with significant ratcheting and an increasing rate during the final part of the test, thus the fracture could be considered as a synergy between fatigue damage and plastic failure. On the contrary, the ratcheting stabilized for high values of R and the tests were finalized without any fracture. Within an intermediate region, for medium/high values of R, a minor ratcheting and the fracture transition have been found. Similarly, for the tests under strain control, low values of R showed fatigue fractures despite a considerable relaxation, conversely for high values of R, the relaxation was limited without any fracture. After reporting the tests on the Haigh plane, the Smith-Watson-Topper equation (SWT) provided the best prediction of the fatigue strength, at least until the intersection with the ultimate stress line, both under stress and strain control loadings. The cyclic behavior of the material was then investigated through several static and cyclic tests on plain specimens. A kinematic hardening Chaboche model, with three parameter couples, was proposed and the values of these parameters derived and discussed. Finally, other tests have been conducted on notched specimens with C geometry and blunt radius, again at high R values. FE analysis allowed the prediction of the stress evolution during the loading cycling, implementing the Chaboche model, and observing a combined effect of ratcheting and relaxation at the notch tip. The stabilized stresses were finally reported on the Haigh diagram and the results were found in agreement with the plain specimen fatigue line
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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