Table of Contents

Stats, Volume 1, Issue 1 (June 2018)

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Research

Open AccessFeature PaperArticle A Nonparametric Statistical Approach to Content Analysis of Items
Received: 6 December 2017 / Revised: 23 January 2018 / Accepted: 25 January 2018 / Published: 1 February 2018
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Abstract
In order to use psychometric instruments to assess a multidimensional construct, we may decompose it into dimensions and, in order to assess each dimension, develop a set of items, so one may assess the construct as a whole, by assessing its dimensions. In
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In order to use psychometric instruments to assess a multidimensional construct, we may decompose it into dimensions and, in order to assess each dimension, develop a set of items, so one may assess the construct as a whole, by assessing its dimensions. In this scenario, content analysis of items aims to verify if the developed items are assessing the dimension they are supposed to by requesting the judgement of specialists in the studied construct about the dimension that the developed items assess. This paper aims to develop a nonparametric statistical approach based on the Cochran’s Q test to analyse the content of items in order to present a practical method to assess the consistency of the content analysis process; this is achieved by the development of a statistical test that seeks to determine if all the specialists have the same capability to judge the items. A simulation study is conducted to check the consistency of the test and it is applied to a real validation process. Full article
Open AccessArticle On Moments of Gamma—Exponentiated Functional Distribution
Received: 24 February 2018 / Revised: 25 March 2018 / Accepted: 27 March 2018 / Published: 30 March 2018
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Abstract
In this note we discuss the development of a new Gamma exponentiated functional GE(α,h) distribution, using the Gamma baseline distribution generating method by Zografos and Balakrishnan. The raw moments of the Gamma exponentiated functional GE(α,
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In this note we discuss the development of a new Gamma exponentiated functional GE ( α , h ) distribution, using the Gamma baseline distribution generating method by Zografos and Balakrishnan. The raw moments of the Gamma exponentiated functional GE ( α , h ) distribution are derived. The related probability distribution class is characterized in terms of Lambert W-function. Full article
Open AccessArticle Probability and Body Composition of Metabolic Syndrome in Young Adults: Use of the Bayes Theorem as Diagnostic Evidence of the Waist-to-Height Ratio
Received: 17 April 2018 / Revised: 8 May 2018 / Accepted: 15 May 2018 / Published: 16 May 2018
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Abstract
Metabolic syndrome (MS) directly increases the risk of cardiovascular diseases. Childhood and adulthood have been the most studied in MS, leaving aside the young adult population. This study aimed to compare the epidemiological probabilities between MS and different anthropometric parameters of body composition.
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Metabolic syndrome (MS) directly increases the risk of cardiovascular diseases. Childhood and adulthood have been the most studied in MS, leaving aside the young adult population. This study aimed to compare the epidemiological probabilities between MS and different anthropometric parameters of body composition. Using a cross-sectional study with the sample of 1351 young adults, different body composition parameters were obtained such as Waist Circumference (WC), Body Mass Index (BMI), Body Fat% (BF%), Waist-to-Height Ratio (WHtR), and Waist-Hip Ratio. The Bayes Theorem was applied to estimate the conditional probability that any subject developed MS with an altered anthropometric parameter of body composition. Areas under receiver operating characteristic curves (AUCs) and adjusted odds ratios of the five parameters were analyzed in their optimal cutoffs. The conditional probability of developing MS with an altered anthropometric parameter was 17% in WHtR, WC, and Waist-hip R. Furthermore, body composition parameters were adjusted by age, BMI, and gender. Only WHtR (OR = 9.43, CI = 3.4–26.13, p < 0.0001), and BF% (OR = 3.18, CI = 1.42–7.13, p = 0.005) were significant, and the sensitivity (84%) and the AUCs (86%) was higher in WHtR than other parameters. In young adults, the WHtR was the best predictor of metabolic syndrome. Full article
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Open AccessArticle A New Extended Birnbaum–Saunders Model: Properties, Regression and Applications
Received: 19 March 2018 / Revised: 24 April 2018 / Accepted: 14 May 2018 / Published: 18 May 2018
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Abstract
We propose an extended fatigue lifetime model called the odd log-logistic Birnbaum–Saunders–Poisson distribution, which includes as special cases the Birnbaum–Saunders and odd log-logistic Birnbaum–Saunders distributions. We obtain some structural properties of the new distribution. We define a new extended regression model based on
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We propose an extended fatigue lifetime model called the odd log-logistic Birnbaum–Saunders–Poisson distribution, which includes as special cases the Birnbaum–Saunders and odd log-logistic Birnbaum–Saunders distributions. We obtain some structural properties of the new distribution. We define a new extended regression model based on the logarithm of the odd log-logistic Birnbaum–Saunders–Poisson random variable. For censored data, we estimate the parameters of the regression model using maximum likelihood. We investigate the accuracy of the maximum likelihood estimates using Monte Carlo simulations. The importance of the proposed models, when compared to existing models, is illustrated by means of two real data sets. Full article
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