Clustering the mixed panel dataset using Gower's distance and k-prototypes algorithms

ABSTRACT

Panel datasets have been increasingly used in economics to analyze complex economic phenomena. Panel data is a two-dimensional array that combines cross-sectional and time series data. Through constructing a panel data matrix, the clustering method is applied to panel data analysis. This method solves the heterogeneity question of the dependent variable, which belongs to panel data, before the analysis. Clustering is a widely used statistical tool in determining subsets in a given dataset. In this article, we present that the mixed panel dataset is clustered by agglomerative hierarchical algorithms based on Gower's distance and by k-prototypes. The performance of these algorithms has been studied on panel data with mixed numerical and categorical features. The effectiveness of these algorithms is compared by using cluster accuracy. An experimental analysis is illustrated on a real dataset using Stata and R package software.     

A graphical evaluation of logistic ridge estimator in mixture experiments

In comparison to other experimental studies, multicollinearity appears frequently in mixture experiments, a special study area of response surface methodology, due to the constraints on the components composing the mixture. In the analysis of mixture experiments by using a special generalized linear model, logistic regression model, multicollinearity causes precision problems in the maximum-likelihood logistic regression estimate. Therefore, effects due to multicollinearity can be reduced to a certain extent by using alternative approaches. One of these approaches is to use biased estimators for the estimation of the coefficients. In this paper, we suggest the use of logistic ridge regression (RR) estimator in the cases where there is multicollinearity during the analysis of mixture experiments using logistic regression. Also, for the selection of the biasing parameter, we use fraction of design space plots for evaluating the effect of the logistic RR estimator with respect to the scaled mean squared error of prediction. The suggested graphical approaches are illustrated on the tumor incidence data set.     

Suicidal behavior and associated factors in sexually abused adolescents

Objectives

The aim of the present study is to determine the rate of suicidal ideation and suicide attempts in sexually abused adolescents and to determine the factors associated with suicidal behavior.

Method

106 adolescents between the ages of 12–18 (94 girls, 12 boys) who were exposed to sexual abuse and referred for the preparation of forensic reports were included in the study. The investigators retrospectively examined the case files, forensic reports and social worker reports.

Results

It has been found that in cases exposed to sexual abuse, suicidal ideation developed in 63.2% (n = 67) of the individuals and 24.5% (n = 26) of them attempted suicide. The rate of suicidal ideation and suicide attempts was higher in cases who live separately from one or both parents, those who have ASD or PTSD after sexual abuse, cases in which abuse involved penetration, cases who were abused by someone known or someone from the family, cases where sexual abuse was accompanied by coercion and physical violence, and those who were exposed to abuse continuously. Among girls, in cases who have suicide history before sexual abuse and those who were abused by more than one abuser, the rate of suicidal ideation was higher.

Conclusion

It has been shown in many studies that sexual abuse in childhood increases the risk of suicidal behavior. Consideration of the factors associated with suicidal behavior in victims of sexual abuse will be helpful to clinicians in preventing suicide attempts.     

Change of attitude toward culture: pre- and post-expatriation experiences of managers

Cultural adjustment and intercultural effectiveness strongly influence international managerial issues, such as organizational success in a local firm, assignment completion, cost of expatriation, and repatriation. Therefore, employees assigned to work in another country need to prepare by learning about that country’s culture before expatriation. Much research has been conducted in the last few decades on the role of culture in expatriation. This study examines how the attitude of expatriate managers toward the importance of culture changes between the pre- and post-expatriation periods. This study is structured as a two-step investigation: (1) pre-expatriation cultural preparation and (2) thoughts on the importance of culture after expatriation. The research sample was South Korean expatriate managers working in Turkey or the US. All participants were reached by the trace method, and the interview data were analyzed in QSR NVivo software with content analysis. The results showed that expatriate managers’ attitude toward the importance of culture changed as a result of expatriation. Pre-expatriation, some participants did not prepare for the new culture. However, after the expatriation experience, all agreed that an understanding of the host culture was important during the assignment. An overseas experience allowed participants to understand the significant role played by culture in their adjustment to the new environment.     

Alternative modeling techniques for the quantal response data in mixture experiments

Mixture experiments are commonly encountered in many fields including chemical, pharmaceutical and consumer product industries. Due to their wide applications, mixture experiments, a special study of response surface methodology, have been given greater attention in both model building and determination of designs compared with other experimental studies. In this paper, some new approaches are suggested on model building and selection for the analysis of the data in mixture experiments by using a special generalized linear models, logistic regression model, proposed by Chen et al. [7]. Generally, the special mixture models, which do not have a constant term, are highly affected by collinearity in modeling the mixture experiments. For this reason, in order to alleviate the undesired effects of collinearity in the analysis of mixture experiments with logistic regression, a new mixture model is defined with an alternative ratio variable. The deviance analysis table is given for standard mixture polynomial models defined by transformations and special mixture models used as linear predictors. The effects of components on the response in the restricted experimental region are given by using an alternative representation of Cox's direction approach. In addition, odds ratio and the confidence intervals of odds ratio are identified according to the chosen reference and control groups. To compare the suggested models, some model selection criteria, graphical odds ratio and the confidence intervals of the odds ratio are used. The advantage of the suggested approaches is illustrated on tumor incidence data set.     

The meaning of bad news management for managers: an explorative research through metaphors

It is a known reality that managers often encounter bad news, and this study explores the question “What is the perspective of managers on bad news management?” in the context of a developing country with rapidly changing conditions. To answer this question, in-depth interviews were conducted with 32 top and middle managers. The results reveal two root metaphors about bad news management in managers’ minds. Managers focus on the past with the “lesson” metaphor and focus on the future with the “opportunity” metaphor. While managing bad news, they draw meaningful inferences from prior experiences and thus become careful and ready. After managing bad news, they have new opportunities to make their organization more mature, developed, and recovered.     

Matrix mean squared error comparisons of some biased estimators with two biasing parameters

To deal with multicollinearity problem, the biased estimators with two biasing parameters have recently attracted much research interest. The aim of this article is to compare one of the last proposals given by Yang and Chang (2010 Yang, H., and X. Chang. 2010. A new two-parameter estimator in linear regression. Communications in Statistics: Theory and Methods 39 (6):923–34.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) with Liu-type estimator (Liu 2003 Liu, K. 2003. Using Liu-type estimator to combat collinearity. Communications in Statistics: Theory and Methods 32 (5):1009–20.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) and k ? d class estimator (Sakallioglu and Kaciranlar 2008 Sakallioglu, S., and S. Kaciranlar. 2008. A new biased estimator based on ridge estimation. Statistical Papers 49:669–89.[Crossref], [Web of Science ®] , [Google Scholar]) under the matrix mean squared error criterion. As well as giving these comparisons theoretically, we support the results with the extended simulation studies and real data example, which show the advantages of the proposal given by Yang and Chang (2010 Yang, H., and X. Chang. 2010. A new two-parameter estimator in linear regression. Communications in Statistics: Theory and Methods 39 (6):923–34.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) over the other proposals with increasing multicollinearity level.     

Ethnic diversity and well-being

This paper investigates how ethnic diversity, measured by immigrants’ nationalities, influences the well-being of the host country. Using panel data from Germany from 1998 to 2012, we find a positive effect of ethnic diversity on the well-being of German natives. Our finding is robust to alternative definitions of ethnic diversity and to the non-random selection of natives and immigrants into regions. The positive effect of ethnic diversity is stronger for immigrant groups that are culturally and economically closer to Germany. Consistent with this result, we document the existence of two mechanisms explaining the influence of ethnic diversity on well-being: productivity—as captured by immigrants’ skills and assimilation—and social capital—particularly in relation to the creation of a multicultural environment.