A WEIGHTED RANK MEASURE OF CORRELATION

Spearman's rank correlation coefficient is not entirely suitable for measuring the correlation between two rankings in some applications because it treats all ranks equally. In 2000, Blest proposed an alternative measure of correlation that gives more importance to higher ranks but has some drawbacks. This paper proposes a weighted rank measure of correlation that weights the distance between two ranks using a linear function of those ranks, giving more importance to higher ranks than lower ones. It analyses its distribution and provides a table of critical values to test whether a given value of the coefficient is significantly different from zero. The paper also summarizes a number of applications for which the new measure is more suitable than Spearman's.     

Redesigning the Downtown of an Expansive Sunbelt City: The Phoenix Case

ABSTRACT

Non-motorized traffic safety is a major public health concern, especially in the sprawling sunbelt cities of the United States. Phoenix is ranked quite high on the number of pedestrian and cyclist crashes in North American cities. This article analyses non-motorist safety incidents in downtown Phoenix. Non-motorist safety concerns were addressed by examining crash types in order to suggest adequate safety treatments. We also demonstrated the use of a countermeasure framework for higher crash locations denominated hotspots. Our findings indicate that it is important to implement a combination of countermeasures to reduce the high number of non-motorist crashes in city centers.     

On the number of local minima for the multidimensional assignment problem

The Multidimensional Assignment Problem (MAP) is an NP-hard combinatorial optimization problem occurring in many applications, such as data association, target tracking, and resource planning. As many solution approaches to this problem rely, at least partly, on local neighborhood search algorithms, the number of local minima affects solution difficulty for these algorithms. This paper investigates the expected number of local minima in randomly generated instances of the MAP. Lower and upper bounds are developed for the expected number of local minima, E[M], in an MAP with iid standard normal coefficients. In a special case of the MAP, a closed-form expression for E[M] is obtained when costs are iid continuous random variables. These results imply that the expected number of local minima is exponential in the number of dimensions of the MAP. Our numerical experiments indicate that larger numbers of local minima have a statistically significant negative effect on the quality of solutions produced by several heuristic algorithms that involve local neighborhood search.Partially supported by the NSF grant DMI-0457473.     

Powerful nonparametric statistics to compare k independent ROC curves

The authors deal with the problem of comparing receiver operating characteristic (ROC) curves from independent samples. From a nonparametric approach, they propose and study three different statistics. Their asymptotic distributions are obtained and a resample plan is considered. In order to study the statistical power of the introduced statistics, a simulation study is carried out. The (observed) results suggest that, for the considered models, the new statistics are more powerful than the usually employed ones (the Venkatraman test and the usual area under the ROC curve criterion) in non-uniform dominance situations and quite good otherwise.     

La formation en cours d'emploi en Europe: déterminants et effets sur les salaires

Partant des données du Panel communautaire de ménages (PCM) pour la période 1995–2001 dans six pays, les auteurs étudient les déterminants des activités de formation et les effets de celle‐ci sur les salaires. A partir de quatre indicateurs caractérisant la formation, ils montrent que, si les estimations par la méthode des moindres carrés ordinaires indiquent que, presque partout, la formation valorise substantiellement les salaires, les estimations avec effets fixes font apparaǐtre une incidence quasi nulle. Les effets sur les salaires seraient donc surestimés faute de prise en compte adéquate de la corrélation entre la formation et d'autres facteurs affectant les salaires.     

Three dimensions of effective mission implementation

Mission statements are generally considered an important tool for strategy implementation. However, several authors have shown that there is a ‘hole’ in the mission theory, which in practice explains the inconsistency in mission statements in many companies because of the lack of motivation related to the mission. This article aims to bridge this gap by analysing the relationship between the mission of a company and its members' motivation. It entails an extension of the mission theory, in which three dimensions of mission development are analysed: formal, dynamic and motivational. On the basis of this framework, three forms of mission consistency are considered to explain the effectiveness of mission implementation: authenticity, coherence and integrity.     

Colonization,coloniality and bio-power: biopolitics in Queensland,Australia

This essay illustrates how a Foucauldian theory of power could re-examine postcolonial, coloniality or colonization contexts, as opposed to the current structuralist and hierarchal theories of understanding power that colonization studies, such as coloniality/modernity or postcolonial studies, use to theorize colonization and race. I argue that a structuralist and hierarchal conceptualization of power relations in understanding colonization and its relationship with racism can be problematic, and that the Foucauldian heterarchical (non-hierarchal) understanding of power relations instead draws a more complete picture of the operation of colonization. In order to demonstrate this claim, I firstly briefly explain how colonization has been mainly theorized through postcolonial and coloniality studies. Then I introduce the relevance of Michel Foucault’s work in the problem of colonization, focusing on his theories of racism and the idea of biopolitics. Then I illustrate how a heterarchical theory of biopolitical power was used against Indigenous Australians in Queensland via the implementation of the Queensland Aboriginals Protection and Restriction of the Sale of Opium Act of 1897. Lastly, I offer some preliminary notes for conceptualizing the global assemblage of the ‘State of Exception’ in the context of colonial Queensland, Australia.     

Intercultural educational alternatives based on sustainability from Mexico: beyond school and cultural belonging

Abstract

This article proposes the articulation of intercultural education and sustainability, linking the recognition of cultural diversity to socio-environmental concerns. This implies transcending formal education and classrooms; moving towards educational modalities that could impact people of different ages, and levels of scholastic achievement, with different needs and demands. We suggest that education is a key to transform structural conditions that have perpetuated inequality, and then to the self-empowerment of indigenous peoples, but that previous models, political basis and forms have not been pertinent, nor do they respond entirely to explicit demands of indigenous peoples. Intercultural education should go beyond simply adding cultural elements to the curriculum. Learning and sharing about ways to connect knowledges and know-how from cultural, social, economic and political distant sources, and ways to visualise and propose autochthonous relevant methods to transform their regions and make these visions of social justice real, are amongst the elements that we consider central to intercultural education. In order to demonstrate this, we analyse an experience of non-formal, collaborative, intercultural education with fisherwomen and youths, making up a learning community and emphasising a dialogue of knowledge for the conservation of their territory.     

Analysis of a marker for cancer of the thyroid with a limit of detection

Limit of detection (LoD) is a common problem in the analysis of data generated by instruments that cannot detect very small concentrations or other quantities, resulting in left-censored measurements. Methods intended for data that are not subject to this problem are often difficult to modify for censoring. We adapt the simulation-extrapolation method, devised originally for fitting models with measurement error, to dealing with LoD in conjunction with a mixture analysis. The application relates the levels of thyroglobulin in individuals with cancer of the thyroid before and after treatment with radioactive iodine I–131. We conclude that the fitted mixture components correspond to levels of effectiveness of the treatment.     

Truncated location-scale non linear regression models

We present a class of truncated non linear regression models for location and scale where the truncated nature of the data is incorporated into the statistical model by assuming that the response variable follows a truncated distribution. The location parameter of the response variable is assumed to be modeled by a continuous non linear function of covariates and unknown parameters. In addition, the proposed model also allows for the scale parameter of the responses to be characterized by a continuous function of the covariates and unknown parameters. Three particular cases of the proposed models are presented by considering the response variable to follow a truncated normal, truncated skew normal, and truncated beta distribution. These truncated non linear regression models are constructed assuming fixed known truncation limits and model parameters are estimated by direct maximization of the log-likelihood using a non linear optimization algorithm. Standardized residuals and diagnostic metrics based on the cases deletion are considered to verify the adequacy of the model and to detect outliers and influential observations. Results based on simulated data are presented to assess the frequentist properties of estimates, and a real data set on soil-water retention from the Buriti Vermelho River Basin database is analyzed using the proposed methodology.