Why is Six Sigma so successful?

There can be little doubt that Motorola, General Electric, Black and Decker, Allied Signal (now Honeywell), ABB and Bombardier, have achieved impressive business performance in recent years. Their annual reports document this success. Furthermore, in several cases, the Annual Report clearly attributes this success to having followed a Six Sigma strategy. Not surprisingly, many other companies wish to learn what Six Sigma can do for them, and their first question is 'What exactly is Six Sigma?'. Unfortunately it is rather difficult, if not impossible, to define Six Sigma in one or two sentences. This paper identifies the essential elements of Six Sigma. Some are obvious, such as the extensive use of statistical techniques by employees known as Blackbelts. However, other more subtle, but very important, features of Six Sigma are concealed within the business culture of these successful companies. It is clear to those who have participated in this success, that any company embarking on Six Sigma will not succeed if it focuses on statistics whilst failing to develop a supporting culture.     

Markov Chain Monte Carlo in small worlds

As the number of applications for Markov Chain Monte Carlo (MCMC) grows, the power of these methods as well as their shortcomings become more apparent. While MCMC yields an almost automatic way to sample a space according to some distribution, its implementations often fall short of this task as they may lead to chains which converge too slowly or get trapped within one mode of a multi-modal space. Moreover, it may be difficult to determine if a chain is only sampling a certain area of the space or if it has indeed reached stationarity. In this paper, we show how a simple modification of the proposal mechanism results in faster convergence of the chain and helps to circumvent the problems described above. This mechanism, which is based on an idea from the field of “small-world” networks, amounts to adding occasional “wild” proposals to any local proposal scheme. We demonstrate through both theory and extensive simulations, that these new proposal distributions can greatly outperform the traditional local proposals when it comes to exploring complex heterogenous spaces and multi-modal distributions. Our method can easily be applied to most, if not all, problems involving MCMC and unlike many other remedies which improve the performance of MCMC it preserves the simplicity of the underlying algorithm.     

Development and Consideration of Global Policies for Managing the Future Risks of Poliovirus Outbreaks: Insights and Lessons Learned Through Modeling

The success of the Global Polio Eradication Initiative promises to bring large benefits, including sustained improvements in quality of life (i.e., cases of paralytic disease and deaths avoided) and costs saved from cessation of vaccination. Obtaining and maintaining these benefits requires that policymakers manage the transition from the current massive use of oral poliovirus vaccine (OPV) to a world without OPV and free of the risks of potential future reintroductions of live polioviruses. This article describes the analytical journey that began in 2001 with a retrospective case study on polio risk management and led to development of dynamic integrated risk, economic, and decision analysis tools to inform global policies for managing the risks of polio. This analytical journey has provided several key insights and lessons learned that will be useful to future analysts involved in similar complex decision-making processes.     

A comparison of objective and subjective measures of clinical competence

The purpose of this study was to determine if objective performance measures from a simulated patient practical examination were related to faculty subjective assessments of surgery students' performance. Another purpose was to determine if those students performing well on a simulated patient practical examination were the same students awarded honor ratings by faculty. Faculty ratings of students (n = 72) on history taking ability, physical exam skills, problem identification, use of investigations, problem integration, patient management, and patient relations skills were correlated with objective measures on these same criteria achieved on a practical exam employing three simulated patient cases. Correlations were also calculated to study the relationship between practical exam scores and honor rating recipients. Results indicated significant relationships between faculty subjective ratings and practical exam outcomes on all practical examination skills except physical exam skills and patient management skills. Findings also indicated the performance of honor students on the practical examination was significantly better than non-honor students on two skills: history-taking and patient relations. The implications of these research findings are discussed.     

‘Wallbanking’, innovativeness and computer attitudes: 25–40-year-old ATM-users on the spot

Attitudes towards ‘wallbanking’ (making use of banking services through an Automated Teller Machine (ATM)) and self-reported frequency of wallbanking have been related to attitudes towards innovations and towards computers. The investigation also included the perception of advantages as well as disadvantages of wallbanking, factors that determine one's choice of a bank, man-machine problems related to the use of an ATM, and demographic factors. Using a sample of 201 respondents in the age range of 25 to 40 years, structural equation modeling revealed that wallbanking attitudes have a major influence on the frequency of using ATMs. The innovativeness attitude ‘New is wasteful’ also showed a clear negative link with the frequency of wallbanking. On the other hand, the relationship between computer attitudes and the frequency of using ATMs had to be rejected. Income and education proved to have an indirect link with the frequency of wallbanking, which refines other research findings. These results may reflect specific financial management characteristics of the age group under investigation.     

Social representations of diversity: multi/intercultural education in a South African urban school 1

The story of School X started in South Africa in 1875. At that time, the school was built for white children only. More than hundred years later, the 1994 elections demarcated the end of the apartheid era and the school enrolled black Xhosa‐speaking children for the first time. As a result, in 2004, 90% of the students were black Xhosa‐speaking. The theoretical perspectives of our study are based on notions of multicultural and intercultural education, and of diversity. Our study is embedded in a socio‐constructivist inquiry paradigm. Using questionnaires and interviews, we aimed to understand the social representations regarding diversity of a principal, a teacher, seven students and four parents in a K‐7 open school. We examined diversity of values, cultures, religions, languages, attitudes, beliefs, behaviors, etc. regarding a multi/intercultural perspective in education. We attempted to discern what the participants’ understandings of diversity were, how they identified diversity, and why they justified their practices and actions with respect to diversity.

The song can only be beautiful if we all play the same tune. (Esmé Goosen, Multimedia, 2004)

This is the title of a painting that is part of an exhibition in Nelson Mandela Metropolitan Museum of Art, Port Elizabeth, South Africa     

Finding your way into employment against all odds? Successful job search of refugees in Austria

Labour market entry poses enormous challenges for recently arrived refugees, ranging from language barriers, devaluation of human capital, unfamiliarity with customs of the job search process to outright discrimination. How can refugees overcome these challenges and quickly enter gainful employment? In this paper, we draw on interviews with 26 male and female refugees from Syria, Afghanistan, Iraq and Iran, conducted in 2017 and 2018, who came to Austria in 2015 and 2014 and who have successfully entered employment. We depict refugees’ own perspectives on and strategies for fast job entry and integration. Personal agency and a proactive approach of seeking and seizing opportunities are key for overcoming initial barriers and entering upon positive integration pathways. At the same time, refugees’ personal agency is essential for establishing social ties to the host society, which also play a crucial role in early labour market integration. Finally, institutions of the Austrian labour market (the ‘apprenticeship’-system) interact with refugees’ agency in most intricate ways, both setting up nearly insurmountable barriers but also providing specific opportunities for refugees.     

PRODUCT DIVERSITY,DEMAND STRUCTURES,AND OPTIMAL TAXATION

This article studies optimal taxation in a general equilibrium macroeconomic model with endogenous entry. We compare the constant elasticity of substitution (CES) model to three alternative demand structures: oligopolistic competition in prices, oligopolistic competition in quantities, and translog preferences. Our economy is characterized by two distortions: a labor distortion due to the misalignment of markups on goods and leisure, and an entry distortion due to the misalignment of the consumer surplus effect and the profit destruction effect of entry. The two distortions interact in determining the wedge between the market‐driven and optimal level of product diversity. We show how optimal labor and entry taxes depend on the prevailing demand structure, the nature and size of entry costs, and the degree of substitutability between goods. (JEL E22, E61, E62)     

Using the End‐User Computing Satisfaction (EUCS) Instrument to Measure Satisfaction with a Web Site

The purpose of this study is to revise and revalidate the End‐User Computing Satisfaction (EUCS) instrument to measure satisfaction with a Web site from a usability perspective. This study is especially important given the increased significance of the Web and the uniqueness of the Web as a computing environment. A total of 176 students participated in a lab simulation that involved a usability evaluation of the Lands' End Web site ( http://www.landsend.com ). Students were asked to complete a set of tasks, record their answers, and then complete the EUCS instrument. Confirmatory factor analysis and invariance analyses were conducted to test the reliability, validity, and generalizability of the revised EUCS. The results show that the EUCS is a valid and robust instrument in the Web environment but that one of the subfactors, timeliness, will need further refinement in the future. Usability practitioners can use the EUCS to measure end‐user satisfaction with a Web site and use the feedback for improving Web‐site design. We describe a case study of an actual usability application that utilized the revised EUCS effectively to support the design of building supply Web sites involving two types of end users, homeowners and contractors. We also propose a typology that researchers can use as a starting point to judge when it is necessary to revalidate an instrument like the EUCS. Finally, we discuss the limitations of our study and present avenues for future research.