An Algorithm for Testing Unidimensionality and Clustering Items in Rasch Measurement

2012 ◽  
Vol 72 (3) ◽  
pp. 375-387 ◽  
Author(s):  
Rudolf Debelak ◽  
Martin Arendasy
Keyword(s):  
Cluster Analysis ◽  
Rasch Model ◽  
Hierarchical Cluster Analysis ◽  
Hierarchical Cluster ◽  
Real Data ◽  
Rasch Measurement ◽  
Local Independence ◽  
New Approach ◽  
Components Analysis ◽  
The Rasch Model

A new approach to identify item clusters fitting the Rasch model is described and evaluated using simulated and real data. The proposed method is based on hierarchical cluster analysis and constructs clusters of items that show a good fit to the Rasch model. It thus gives an estimate of the number of independent scales satisfying the postulates of sufficiency of total number of correctly answered items for a person’s proficiency, unidimensionality, and local independence that can be constructed from an item set. The method is also compared with the application of a principal components analysis based on tetrachoric correlations. In general, the proposed method was shown to provide practically usable results especially for large person samples.

Chemistry research in Europe: A publication analysis (2006–2016)

2019 ◽  
pp. 016555151986549
Author(s):  
Hakan Kaygusuz
Keyword(s):  
Cluster Analysis ◽  
Principal Components Analysis ◽  
Principal Components ◽  
Hierarchical Cluster Analysis ◽  
Hierarchical Cluster ◽  
Polymer Science ◽  
Chemistry Research ◽  
Research Outcome ◽  
Components Analysis ◽  
Number Of Publications

In this article, chemistry research in 51 different European countries between years 2006 and 2016 was studied using statistical methods. This study consists of two parts: In the first part, different economical, institutional and citation parameters were correlated with the number of publications, citations and chemical industry numbers using principal components analysis and hierarchical cluster analysis. The results of the first part indicated that economical and geographical parameters directly affect the chemistry research outcome. In the second part, research in branches of chemistry and related disciplines such as analytical chemistry, polymer science and physical chemistry were analysed using principal components analysis and hierarchical cluster analysis for each country. Publication data were collected as the number of chemistry publications (in Science Citation Index–Expanded (SCI-E)) between years 2006 and 2016 in different chemistry subdisciplines and related scientific areas. Results of the second part of the study produced geographical and economical clusters of countries, interestingly, without addition of any geographical data.

scholarly journals In Vitro Trials of Dittrichia graveolens Essential Oil Combined with Antibiotics

2016 ◽  
Vol 11 (6) ◽  
pp. 1934578X1601100 ◽  
Author(s):  
Dragoljub L. Miladinović ◽  
Budimir S. Ilić ◽  
Branislava D. Kocić ◽  
Marija S. Marković ◽  
Ljiljana C. Miladinović
Keyword(s):  
Cluster Analysis ◽  
Gas Chromatography ◽  
Antibacterial Activity ◽  
Chemical Composition ◽  
Essential Oil ◽  
Hierarchical Cluster Analysis ◽  
Hierarchical Cluster ◽  
Bacterial Strains ◽  
Components Analysis

The chemical composition and antibacterial activity of Dittrichia graveolens (L.) Greuter essential oil were examined. Gas chromatography and gas chromatography/mass spectrometry were used to analyze the chemical composition of the essential oil. The antibacterial activity was investigated by the broth microdilution method against thirteen bacterial strains. The interactions of the essential oil and three standard antibiotics: chloramphenicol, tetracycline and streptomycin toward five selected strains were evaluated using the microdilution checkerboard assay in combination with chemometric methods: principal components analysis and hierarchical cluster analysis. Oxygenated monoterpenes were the most abundant compound class in the essential oil (40.6%), with bornyl acetate (21.7%) as the major compound. The essential oil exhibited slight antibacterial activity against the tested bacterial strains in vitro, but the combinations D. graveolens essential oil-chloramphenicol and D. graveo/ens-tetracycline exhibited mostly synergistic or additive interactions. These combinations reduced the minimum effective dose of the antibiotics and, consequently, minimized their adverse side effects. In contrast, the association of D. graveolens essential oil and streptomycin was characterized by strong antagonistic interactions against E. coli ATCC 25922, S. aureus ATCC 29213 and P. aeruginosa ATCC 27853. In the principal components analysis (PCA) and hierarchical cluster analysis (HCA), streptomycin against these bacterial strains stood out and formed a separate group.

scholarly journals A multidimensional taxonomy of developmental States

2020 ◽  
Vol 51 (201) ◽  
Author(s):  
Sergio Tezanos ◽  
Fernando De la Cruz
Keyword(s):  
Cluster Analysis ◽  
Human Development ◽  
Hierarchical Cluster Analysis ◽  
East Asian ◽  
Hierarchical Cluster ◽  
New Approach ◽  
East Asian Region ◽  
Asian Region ◽  
Developmental States

This paper proposes a new approach to the classification of Developmental States (DS) based on their public efforts to foster human development. We conceptualize DS within a multidimensional framework that includes three main dimensions (economic, social and democratic), and run a hierarchical cluster analysis for 112 countries in order to build a multidimensional taxonomy of DS. We propose a countryclassification and characterize three country-groups with different developmental public efforts: i) the human development States; ii) the unbalanced developmental States and iii) the non-developmental States. Our multidimensional taxonomy offers a more complex understanding of the variety of public efforts devoted to promote human development, thus overcoming the restricted –economical– conception of DS, which is mainly focused to the East Asian region

scholarly journals Clustering of Symbolic Data based on Affinity Coefficient: Application to a Real Data Set

2013 ◽  
Vol 50 (1) ◽  
pp. 27-38
Author(s):  
Áurea Sousa ◽  
Helena Bacelar-Nicolau ◽  
Fernando C. Nicolau ◽  
Osvaldo Silva
Keyword(s):  
Cluster Analysis ◽  
Hierarchical Cluster Analysis ◽  
Probabilistic Approach ◽  
Hierarchical Cluster ◽  
Real Data ◽  
Interval Data ◽  
Parametric Family ◽  
Complex Data ◽  
Data Set ◽  
Symbolic Data

SUMMARY In this paper, we illustrate an application of Ascendant Hierarchical Cluster Analysis (AHCA) to complex data taken from the literature (interval data), based on the standardized weighted generalized affinity coefficient, by the method of Wald and Wolfowitz. The probabilistic aggregation criteria used belong to a parametric family of methods under the probabilistic approach of AHCA, named VL methodology. Finally, we compare the results achieved using our approach with those obtained by other authors.

A new approach of testing the Rasch model

2011 ◽  
Author(s):  
Klaus Kubinger ◽  
D. Rasch ◽  
T. Yanagida
Keyword(s):  
Rasch Model ◽  
New Approach ◽  
The Rasch Model

Extraordinary circumstances: Covid-19 – Italian Serie A scenario

2021 ◽  
pp. 175433712110192
Author(s):  
Milan Radojicic ◽  
Aleksandar Djokovic ◽  
Nikola Cvetkovic
Keyword(s):  
Cluster Analysis ◽  
Hierarchical Cluster Analysis ◽  
Hierarchical Cluster ◽  
Round Robin ◽  
The Past ◽  
Novel Approach ◽  
Round Robin Tournaments

Unpredictable and uncontrollable situations have happened throughout history. Inevitably, such situations have an impact on various spheres of life. The coronavirus disease 2019 has affected many of them, including sports. The ban on social gatherings has caused the cancellation of many sports competitions. This paper proposes a methodology based on hierarchical cluster analysis (HCA) that can be applied when a need occurs to end an interrupted tournament and the conditions for playing the remaining matches are far from ideal. The proposed methodology is based on how to conclude the season for Serie A, a top-division football league in Italy. The analysis showed that it is reasonable to play 14 instead of the 124 remaining matches of the 2019–2020 season to conclude the championship. The proposed methodology was tested on the past 10 seasons of the Serie A, and its effectiveness was confirmed. This novel approach can be used in any other sport where round-robin tournaments exist.

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