On the joint distribution of placement statistics under progressive censoring and applications to precedence test

In reliability and survival analysis, comparison of two or more populations is an important problem. For example, while comparing a treatment group with a control group, one may be interested in determining whether the observations in the treatment group have a longer lifetime than those from the control group, that is, whether the treatment is effective or not. In such a study, it would be extremely valuable to make a decision based on early failures. In this paper, we consider independent progressively Type-II censored random samples from two populations with cumulative distribution function's (cdf) F(·)$F(·)$ and G(·)$G(·)$ respectively, and discuss a precedence test for testing the equality of the two distributions based on placements. For this purpose, we derive the joint distribution of the first l   placement statistics from the progressively censored sample from F(·)$F(·)$. We then derive the exact null distribution of the precedence test statistic which is simply the sum of the placements. We provide the rejection regions for fixed levels of significance and various sample sizes and different progressive censoring schemes.     

Multiproduct,Multicriteria Model for Supplier Selection with Product Life‐Cycle Considerations

In industrial purchasing contexts firms often procure a set of products from the same suppliers to benefit from economies of scale and scope. These products are often at different stages of their respective product life cycles (PLCs). Firms consider multiple criteria in purchasing such products, and the relative importance of these criteria varies depending on the PLC stage of a given product. Therefore, a firm should select suppliers and choose sourcing arrangements such that product requirements across multiple criteria are satisfied over time. The extant models in sourcing literature for evaluating and selecting suppliers for a portfolio of products have not considered this important and practical issue faced by firms. This article proposes a mathematical model that effectively addresses this issue and contributes to the sourcing literature by demonstrating an approach for optimally selecting suppliers and supplier bids given the relative importance of multiple criteria across multiple products over their PLC. The application of the model on a hypothetical data set illustrates the strategic and tactical significance of such considerations.     

Some non-parametric tests for duration dependence: an application to UK business cycle data

A distinction between Fisher's implied data-generating process for Monte Carlo cycles and the more general Markov process leads to non-parametric tests for duration dependence. Tests are based on the method of moments, Tauchen's generalized method of moments (GMM) procedure, and a statistic whose null distribution probability limit is zero. Using finite-sample critical values obtained by Monte Carlo methods, our test results are remarkably consistent. The null distribution of the GMM test statistic for samples of the size considered is distinctly non-normal, so that asymptotic critical values give erroneous results. The tests are applied to UK business cycle data for 1854-1992. There is evidence for duration dependence in expansions but not in contractions.     

Some issues related to the topological aggregation of preferences

This paper deals with the topological approach to social choice theory initiated by Chichilnisky. We study several issues concerning the existence and uniqueness of Chichilnisky rules defined on preference spaces. We show that on topological vector spaces the only additive, anonymous, and unanimous aggregation n-rule is the convex mean. We study the case of infinite agents and show that an infinite Chichilnisky rule might be considered as the limit of rules for finitely many agents. Finally, we show that under some restrictions on the preference space, the existence of a Chichilnisky rule for every finite case implies the existence of a weak Chichilnisky rule for the infinite case.     

Label‐ and Level‐Invariant Graphical Log‐Linear Models

We introduce two types of graphical log‐linear models: label‐ and level‐invariant models for triangle‐free graphs. These models generalise symmetry concepts in graphical log‐linear models and provide a tool with which to model symmetry in the discrete case. A label‐invariant model is category‐invariant and is preserved after permuting some of the vertices according to transformations that maintain the graph, whereas a level‐invariant model equates expected frequencies according to a given set of permutations. These new models can both be seen as instances of a new type of graphical log‐linear model termed the restricted graphical log‐linear model, or RGLL, in which equality restrictions on subsets of main effects and first‐order interactions are imposed. Their likelihood equations and graphical representation can be obtained from those derived for the RGLL models.     

Internationalization,Innovation and Institutions: The 3 I's Underpinning the Competitiveness of Emerging Market Firms

The past decade has seen an increase in the extent of research focused on and around emerging market firms (EMFs) and their rising levels of competitiveness in both their home markets and more importantly in the global market place. At the same time, the practitioner-oriented literature has been documenting a growing number of corporate success stories that originate in emerging market economies. We posit that the growing prominence of EMFs is a result of three interrelated phenomena: the fast-paced internationalization of EMFs into both developing and developed market economies; the rapidly increasing extent to which business enterprises in emerging economies are focusing on knowledge-intensive processes and innovation; and the continuous evolution of institutions in these markets, particularly in terms of economic liberalization.     

The effects of wage flexibility on activity and employment in Spain

In this paper we estimate the macroeconomic effects of the greater wage and firms’ internal flexibility promoted by the economic policies implemented since 2012, which changed markedly Spanish labour regulations. To do so, we propose a structural VAR that allows us to break down changes in main macroeconomic variables into different structural shocks. From a policy perspective, the estimation of the structural shocks allows us to simulate a counterfactual scenario, whereby we conclude that the effects of less rigid labour market are positive and significant. Our results suggest that, if these policies were implemented at the beginning of the crisis, they could have avoided a significant part of the falls in GDP and employment.     

Editor's Choice: An Interview with Hans Joas

The interview explores multiple aspects of social theory, most of them directly related to Joas's theory and others to symbolic interactionism and Goffman. The first part delves into Joas's theory in three respects. First, a clarifying note on a common misunderstanding about his book The Creativity of Action. Second, a clarification on the scope of his theoretical endeavor, and third, a look into his coming books to have a better grasp of the course that his theory is taking. The second part is dedicated to symbolic interactionism and Goffman. Firstly, Joas's opinion about the theoretical relationship between symbolic interactionism and macrosociology is emphasized, secondly, his opinion about the pertinence of locating Goffman within symbolic interactionism is stated, and thirdly, a brief commentary about the relationship between Joas's theory and Goffman's is introduced.     

The role of social anxiety in volunteering

The volunteer management literature suggests that the most effective means of recruitment is personal asking. However, agencies that apply this method do not report the expected success in volunteer recruitment. Often they face the volunteer recruitment fallacy: those people assumed to be interested in volunteering do not necessarily volunteer. Based on the literature of shyness or social anxiety and on empirical observations, this article suggests that social anxiety often deters volunteering by new recruits. We hypothesize that people with greater levels of social anxiety will be less likely to volunteer. Furthermore, we hypothesize that people with high social anxiety will prefer to give monetary support to worthy causes rather than volunteer their time, and if they do choose to volunteer, they will do so alongside friends. Our hypotheses are supported based on the findings from a large‐scale nonrandom sample in North America. We suggest how to avoid the volunteer recruitment fallacy by creating a personal environment in which high‐social‐anxiety recruits feel safe and accepted. By removing the fear of being negatively judged by strangers as they enter the agency and creating a more personal approach, new recruits may have a higher probability of becoming long‐term and consistent volunteers.     

‘Young,Fun, and Free:’ Episodic Volunteers in Ghana,South Africa and Tanzania

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - As scholarship on episodic volunteering expands, researchers question if episodic volunteering is similar to, and/or...