Simple and Globally Convergent Methods for Accelerating the Convergence of Any EM Algorithm

Abstract.  The expectation-maximization (EM) algorithm is a popular approach for obtaining maximum likelihood estimates in incomplete data problems because of its simplicity and stability (e.g. monotonic increase of likelihood). However, in many applications the stability of EM is attained at the expense of slow, linear convergence. We have developed a new class of iterative schemes, called squared iterative methods (SQUAREM), to accelerate EM, without compromising on simplicity and stability. SQUAREM generally achieves superlinear convergence in problems with a large fraction of missing information. Globally convergent schemes are easily obtained by viewing SQUAREM as a continuation of EM. SQUAREM is especially attractive in high-dimensional problems, and in problems where model-specific analytic insights are not available. SQUAREM can be readily implemented as an 'off-the-shelf' accelerator of any EM-type algorithm, as it only requires the EM parameter updating. We present four examples to demonstrate the effectiveness of SQUAREM. A general-purpose implementation (written in R) is available.     

EXTENDING THE BOUNDARIES OF OPERATIONS MANAGEMENT: AN INTERNATIONAL FIELD-STUDIES APPROACH INTEGRATING INFORMATION SYSTEMS

Continued globalization, extensive use of information technologies, increasing cross-functional dependencies, and new organizational forms are rapidly changing the learning context of operations management. This paper describes an example of a mba elective course that has been created to address and learn from these new realities. We have taken a process view of the global firm, focusing mainly on the new product/service development, order fulfillment, and supply chain/ after-sales service processes. We have designed our course to contain most of the traditional topics in operations management (om) with information systems (is) woven in to support the key business processes. Our underlying belief is that these two functional areas should be seen as a blend, a seamless merging of the two fields, to obtain a competitive advantage. Besides teaching om and is in this integrated manner, the course engages in face-to-face student consulting projects with multinational companies. This paper describes our rationale for the course design and how it has been implemented over the last 6 years-as well as our plans for the future.     

QUALITY AND WORK FORCE MANAGEMENT PRACTICES: THE MANAGERIAL PERFORMANCE IMPLICATION

Quality has been in the limelight as organizations have sought to create a competitive advantage and theorists have sought to understand the implications of quality management. This paper examines the synergistic effects of the quality emphasis in the organizations, the use of appropriate work force management practices, and the managerial performance outcomes as interactive phenomena. Using data from multiple levels of employees in manufacturing units in various industries, we tested hypotheses regarding the managerial performance impact of the synergy in work force management practices and the quality emphasis. The results indicate that the effectiveness of work force management practices in enhancing managerial performance varies with the emphasis on quality that is manifested by meeting and exceeding customer needs and preferences through accurate, consistent, reliable, and durable products, and by making design changes in the products as desired by the customer.     

Globalization and Changing Patterns of Social Mobilization in Urban India

Recent developments around the globe – from organization into forums such as the World Social Forum to smaller protests – have necessitated a review of the notion of movements/mobilizations. There is an enhanced focus on ‘mobilizing/organizing’ masses. The character of mobilizations is radically transformed and is in a constant flux leading to explorations of newer ‘experiments’. Central to such a conceptualization, given the state of mobilizations worldwide, is the need to grapple with the causal factors and the dialectics of systemic dynamics and mobilizations. This paper seeks to comprehend the dynamics of mobilizations, their rise and fall in the light of contemporary developments of rampant consumerism and individualization resulting in shrinking collective spaces. It argues that in the transformed setting, when liberalism coexists with mounting coercion of private capital through state as well as non-state institutions, mobilizations of changed character will be ultimate expressions of resistance leading in due course to a macro-assertion. Such a debate has not been taken up seriously in India with the same intensity as in the Latin American context or in Western sociology. The arguments made in the paper are based on interviews with activists, interaction with activists and their experiences in different meetings as well as research based on secondary material.     

SERVICE-BASED MANUFACTURING: THE SERVICE FACTORY

Evidence suggests that factory-based service will become the next form of competition among manufacturers. If this is true, then manufacturing executives will have to obtain a clear understanding of the service capabilities of their plants and adjust their strategies accordingly. We define a set of factory-based services, information, problem solving, sales, and support, and suggest that they be considered in developing manufacturing strategy. Several propositions provide a framework for future research by linking service performance variables to conventionally accepted manufacturing performance variables.