COWORDS: a probabilistic model for multiple word clouds

Word clouds constitute one of the most popular statistical tools for the visual analysis of text documents because they provide users with a quick and intuitive understanding of the content. Despite their popularity for visualizing single documents, word clouds are not appropriate to compare different text documents. Independently generating word clouds for each document leads to configurations where the same word is typically located in widely different positions. This makes it very difficult to compare two or more word clouds. This paper introduces COWORDS, a new stochastic algorithm to create multiple word clouds, including one for each document. The shared words in multiple documents are placed in the same position in all clouds. Similar documents produce similar and compact clouds, making it easier to simultaneously compare and interpret several word clouds. The algorithm is based on a probability distribution in which the most probable configurations are those with a desirable visual aspect, such as a low value for the total distance between the words in all clouds. The algorithm output is a set of word clouds that are randomly selected from this probability distribution. The selection procedure uses a Markov chain Monte Carlo simulation method. We present several examples that illustrate the performance and visual results that can be obtained by our algorithm.     

Estimating the population proportion in modified ranked set sampling methods

In this paper, proportion estimators and associated variance estimators are proposed for a binary variable with a concomitant variable based on modified ranked set sampling methods, which are extreme ranked set sampling (ERSS), median ranked set sampling (MRSS), percentile ranked set sampling (Per-RSS) and L ranked set sampling (LRSS) methods. The Monte Carlo simulation study is performed to compare the performance of the estimators based on bias, mean squared error, and relative efficiency for different levels of correlation coefficient, set and cycle sizes under normal and log-normal distributions. Moreover, the study is supported with real data application.     

Bayesian unit-root tests for Stochastic Volatility models

In this article, we consider Bayesian inference procedures to test for a unit root in Stochastic Volatility (SV) models. Unit-root tests for the persistence parameter of the SV models, based on the Bayes Factor (BF), have been recently introduced in the literature. In contrast, we propose a flexible class of priors that is non-informative over the entire support of the persistence parameter (including the non-stationarity region). In addition, we show that our model fitting procedure is computationally efficient (using the software WinBUGS). Finally, we show that our proposed test procedures have good frequentist properties in terms of achieving high statistical power, while maintaining low total error rates. We illustrate the above features of our method by extensive simulation studies, followed by an application to a real data set on exchange rates.     

Social Competence in Preschool Children: Replication of Results and Clarification of a Hierarchical Measurement Model

This study tested assumptions and conclusions reached in an earlier confirmatory factor analysis (CFA) study of the social competence (SC) construct for preschool children. Two samples (total N = 408; a new Portuguese sample and one from US samples that had participated in the original study) contributed data. Seven SC indicators were tested for mean differences across age, sex, and sample. Significant sex differences were found for peer acceptance (favoring girls) and for initiating affectively neutral interactions (boys had higher rates), and the sex by sample interaction also was significant for initiating interactions (i.e., effect significant only in the Portuguese sample). In CFAs, the hypothesized structure of SC fits the data and was invariant across sample and age within sample in both measurement and structural tests. The model was invariant at the measurement level for sex within sample tests, but not at the structural level. The results replicate and extend understandings of SC reported in the original study.     

Workgroup interdependence and satisfaction from a developmental perspective: the moderating role of the group’s life cycle stage / Interdependencia y satisfacción en el grupo de trabajo desde la perspectiva del desarrollo: el rol moderador de la fase del ciclo de vida grupal

From a developmental perspective, workgroups adjust and modify the way they function over time. The present study aims to test, at the group level, the moderating role of the group’s life phase in the relationship between workgroup interdependence ties in terms of task, outcome and functions, assessed by social network density and group satisfaction. A sample of 84 teams from various companies participated in this research. The results showed that the group’s development phase determines the way that outcome interdependence density in teams is associated with satisfaction and reveal the existence of differences between the second and fourth development stages. Therefore, the group’s life cycle stage should be considered as a relevant variable in research and intervention with groups in the workplace.     

Concurrent training protocol for men with androgen deficiency in the aging male: a randomized clinical trial

Background: The androgen deficiency in the aging male (ADAM) affects physical, sexual, and psychological aspects with characteristics symptoms of middle-aged men. The practice of regular physical activity and physical exercise can attenuate these symptoms. The aim of this randomized clinical trial is to propose a physical exercise protocol based on concurrent training for middle-aged men with ADAM.

Method: Randomized clinical trial with a 6-month intervention will randomly divided into two groups: experimental group (EG) and control group (CG). Four evaluations will be carried out, (1) pre-intervention; (2) in the first month of intervention; (3) in the third month of intervention; (4) post-intervention, evaluating: physical, psychological, sexual, and hormonal aspects. The intervention protocol with concurrent training will have duration of 6 months; frequency of 3 times weekly, with 60?min per session. The two-way ANOVA test will be used for the inter-group and intra-group comparisons with repeated measurements, and also Sydak’s comparison test.

Conclusion: This protocol was developed with the intent of easing the symptoms of ADAM. In addition, it is believed that the concurrent training protocol could be capable to recover hormonal, physical, psychological, and sexual aspect of middle-aged men with ADAM.     

An ant colony optimization approach for the proportionate multiprocessor open shop

Multiprocessor open shop makes a generalization to classical open shop by allowing parallel machines for the same task. Scheduling of this shop environment to minimize the makespan is a strongly NP-Hard problem. Despite its wide application areas in industry, the research in the field is still limited. In this paper, the proportionate case is considered where a task requires a fixed processing time independent of the job identity. A novel highly efficient solution representation is developed for the problem. An ant colony optimization model based on this representation is proposed with makespan minimization objective. It carries out a random exploration of the solution space and allows to search for good solution characteristics in a less time-consuming way. The algorithm performs full exploitation of search knowledge, and it successfully incorporates problem knowledge. To increase solution quality, a local exploration approach analogous to a local search, is further employed on the solution constructed. The proposed algorithm is tested over 100 benchmark instances from the literature. It outperforms the current state-of-the-art algorithm both in terms of solution quality and computational time.

     

A Bayesian approach for zero-modified Skellam model with Hamiltonian MCMC

Statistical Methods & Applications - In this paper is presented the zero-modified poisson difference and present possible applications of them in the analysis of paired count data. The...     

Optimal classification scores based on multivariate marker transformations

AStA Advances in Statistical Analysis - Modern science frequently involves the study of complex relationships among effects and factors. Flexible statistical tools are commonly used to visualize...