A NOTE ON PROCEDURES FOR TESTING THE QUALITY OF A CLUSTERING OF A SET OF OBJECTS

Despite the increased application of cluster analysis in decision sciences, few attempts have been made to derive hypothesis-testing procedures for the evaluation of clustering solutions. In fact, the present paper shows that at least one such attempt failed to specify a meaningful sampling distribution for the test procedure. An alternative index based on the concept of point-biserial correlation is proposed as a possible recovery measure. The index is subsequently used to form the basis of a valid statistical test for the existence of cluster structure.     

PRACTICAL SIGNIFICANCE AND PARTITIONING VARIANCE IN DISCRIMINANT ANALYSIS

This note sets forth a method for obtaining viable estimates of total discriminatory power in a discriminant analysis. In addition, a technique based upon this methodisgiven for assessing the overall relative importance of each predictor variable regardless of the number of discriminant functions. Two examples are given to illustrate application of the method.     

Complexity,technology and the future of transformative politics

ABSTRACT

This paper argues that the ‘open space’ idea remains the key source of strength for the World Social Forum as a tool for transformative, liberatory politics. We suggest that this space can be seen as inhabited by two political identities formed on the basis of what we call the conventional left narrative on the one hand and the civilizational narrative on the other. We propose that WSF can continue to fulfil its mission well by serving as a forum where political and social activists and intellectuals can meet and learn from each other to overcome their current weaknesses. Key to such overcoming, we suggest, is that technology and complexity are politicized – a task which may be difficult but the avoidance of which may be irresponsible.     

The safety–quality dominant view of food chain integrity: Implications for consumer-centric food chain governance

Food chain integrity demands strengthening the position of end consumers in the food system. Shaping this consumer-centric agenda leads to a multi-dimensional quest where actors in the food chain need to remodel their production, processing and disclosure norms by focusing on end consumers’ expectations. Food chain integrity so far has largely been explained using the angles of fraud and criminality to mainstream the criticality of curbing intentional contamination in food chain operations. However, the view which accounts for how food safety and food quality expand the understanding of food chain integrity remains underdeveloped. Addressing this concern, we conceptualize the interaction space between the notions of food chain integrity, food safety and food quality using a unifying lens of supply chain governance in the food chain. In doing so, we outline the safety and quality-oriented arcs of food chain governance that are instrumental in creating consumer-centric processes. Drawing from systematic reviews, a multi-disciplinary article set is constructed involving the scholarships of food sector management, logistics and supply chain management, marketing and general management. The key findings outline five principal themes to notionally characterize the targeted interaction space and set the foundation of consumer-centric supply chain governance for food chain integrity. Besides discussing diverse governance areas such as industrial co-regulation, newer emphasis areas for internal/external chain integration and the need for consumer integration in food chain processes, the thematic leads are distilled further to outline macro- and micro-level arcs of consumer-centric food chain governance along with strategic pathways for future research.     

On metric dimension of plane graphs with $$\frac{m}{2}$$ number of 10 sided faces

Journal of Combinatorial Optimization - Let $$\Gamma =\Gamma (V, E)$$ be a simple (multiple edges and loops are not considered), connected (every pair of distinct vertices are joined by a path),...     

Bias correction in logistic regression with missing categorical covariates

Logistic regression plays an important role in many fields. In practice, we often encounter missing covariates in different applied sectors, particularly in biomedical sciences. Ibrahim (1990) proposed a method to handle missing covariates in generalized linear model (GLM) setup. It is well known that logistic regression estimates using small or medium sized missing data are biased. Considering the missing data that are missing at random, in this paper we have reduced the bias by two methods; first we have derived a closed form bias expression using Cox and Snell (1968), and second we have used likelihood based modification similar to Firth (1993). Here we have analytically shown that the Firth type likelihood modification in Ibrahim led to the second order bias reduction. The proposed methods are simple to apply on an existing method, need no analytical work, with the exception of a little change in the optimization function. We have carried out extensive simulation studies comparing the methods, and our simulation results are also supported by a real world data.