Variance Estimation and Asymptotic Confidence Bands for the Mean Estimator of Sampled Functional Data with High Entropy Unequal Probability Sampling Designs

For fixed size sampling designs with high entropy, it is well known that the variance of the Horvitz–Thompson estimator can be approximated by the Hájek formula. The interest of this asymptotic variance approximation is that it only involves the first order inclusion probabilities of the statistical units. We extend this variance formula when the variable under study is functional, and we prove, under general conditions on the regularity of the individual trajectories and the sampling design, that we can get a uniformly convergent estimator of the variance function of the Horvitz–Thompson estimator of the mean function. Rates of convergence to the true variance function are given for the rejective sampling. We deduce, under conditions on the entropy of the sampling design, that it is possible to build confidence bands whose coverage is asymptotically the desired one via simulation of Gaussian processes with variance function given by the Hájek formula. Finally, the accuracy of the proposed variance estimator is evaluated on samples of electricity consumption data measured every half an hour over a period of 1 week.     

Ambiguous Loss Research,Theory, and Practice: Reflections After 9/11

This article contains an overview of three decades of research, theory development, and clinical application about ambiguous loss. Although the work includes both physical and psychological types of ambiguous loss, the focus is the aftermath of 9/11 (September 11, 2001), when the World Trade Center collapsed following terrorist attacks. On the basis of her previous work, the author was asked to design an intervention for families of the missing. She reflects on what she learned from this unexpected test and presents new propositions and hypotheses to stimulate further research and theory that is more inclusive of diversity. She suggests that scholars should focus more on universal family experience. Ambiguous loss is just one example. Encouraging researchers and practitioners to collaborate in theory development, she concludes that research‐based theory is essential to inform interventions in unexpected times of terror, and in everyday life.     

Engaging Professionals in Sustainable Workplace Innovation: Medical Doctors and Institutional Work

This paper investigates the role of medical professionals in the success and longevity of the implementation of workplace innovation and organizational change in the Accident and Emergency (A&E) Departments of two large public hospitals, in Australia and Canada, during the introduction of process improvement using Lean Management (LM) methodologies. We ask why and how doctors resist, influence or enable LM initiatives in healthcare. Using a qualitative methodology, we contribute to institutional work theory by unpacking the complex forms of boundary and practice work undertaken by key actors who effectively use their professional status and power to enable practice changes to be embedded. Our findings lend support to the importance of the involvement and ownership of senior doctors in the design, introduction and implementation of successful workplace innovation and organizational change. Senior doctors use their professional expertise, positional and political power at the industry, organization and workplace levels to influence strategically the use of resources designated for workplace innovation to improve efficiencies, quality of patient care and maintain their dominance. The significant organizational change achieved reflected the ownership and leadership of the workplace innovation by senior doctors in ‘hybrid roles’ who captured the rhetoric and minimized adversarialism among key stakeholders.     

Targeting lean process improvement projects for maximum financial impact

This empirical paper details a 12-month applied research project at a UK low-volume manufacturer of large vehicles. The industry problem from which this study originates was a concern over the subjective nature with which the firm’s existing lean intervention projects were being targeted (prioritised and selected). A structured literature review on this topic was unable to identify any objective decision support mechanism for doing so; one that encompassed financial as well as operational criteria. The resultant study was organised around an established seven-step action research framework. The main body of evidence was derived from extensive analysis of financial and operational data extracted from the firm’s enterprise resource planning system, along with two structured workshops that each involved multiple informants drawn from the firm’s production centres and its accountancy department. Supplementary primary research was provided in the guise of numerous unstructured interviews to validate data and from observation of shop floor practices. The main contribution of this article is identifying and addressing the gap highlighted above, by developing and testing a financially driven method for objectively targeting process improvement interventions within this large and geographically dispersed operation. This innovative method includes five new constituent techniques.     

Task analysis of healthcare delivery: A case study

Human error and medical error are highly known as contributors to patient safety [Institute of Medicine (IOM), November 1999. To err is human: building a safer health system. Available at: http://www.nap.edu/openbook/0309068371/html/11.html (accessed 05.03.07); Institute of Medicine (IOM), March 2001. Crossing the quality chasm: a new health system for the 21st century. Available at: http://www.nap.edu/openbook/0309072808/html (accessed 05.03.07); Joint Commission on Accreditation of Healthcare Organizations (JCAHO), 2007. Failure mode, effect, and criticality analysis (FMECA) worksheet. Available at: http://www.jcaho.org (accessed 24.06.07)]. A study was performed to identify the process flow affiliated with elder patients transitioning through different continuums of emergency and non-emergency care. This research is part of a larger research effort to develop and implement a web-based healthcare system that enables hospitals and nursing homes to share patient information resulting in increased knowledge of a patient's medical history, decreased errors and enhanced patient safety. Future research efforts for this study are also presented.     

Nonparametric predictive comparison of lifetime data under progressive censoring

In reliability and lifetime testing, comparison of two groups of data is a common problem. It is often attractive, or even necessary, to make a quick and efficient decision in order to save time and costs. This paper presents a nonparametric predictive inference (NPI) approach to compare two groups, say X and Y, when one (or both) is (are) progressively censored. NPI can easily be applied to different types of progressive censoring schemes. NPI is a statistical approach based on few assumptions, with inferences strongly based on data and with uncertainty quantified via lower and upper probabilities. These inferences consider the event that the lifetime of a future unit from Y is greater than the lifetime of a future unit from X.     

The wages of sweat: A social history perspective on the fight against sweatshops

The social history of the fight against sweatshops casts light on the current movement in favor of corporate social responsibility. But making the head of a chain of subcontractors responsible for seeing to the well-being of those at the end of the chain is not contemporaneous with present-day globalization and North/South relations. Since the 19th century, when the sweatshop system appeared, those who champion the workers have pointed a finger at those who, though they only exercise indirect control, profit from their exploitation. As our historical analysis emphasizes, though in other contexts the issue of poor working conditions sometimes found solutions that (partially) avoided holding the principal liable, what characterizes the anti-sweatshop movement in the context of globalization is its nearly exclusive focus on bringing pressure to bear on the contractor at the head of the chain.     

Design and implementation of a Drum-Buffer-Rope pull-system

Purpose: This paper investigates the selection, design and implementation of a Drum-Buffer-Rope (DBR) type of production pull-system in a panel fabrication plant characterised by extensive shared, batch resource resources within a low volume UK manufacturer of large vehicles. This was the second of a series of two related research projects conducted under the aegis of a Lean initiative at this case firm.

Design/methodology/approach: A purposively selected longitudinal case study conducted over 24?months and organised around a two phase research design. The initial body of evidence included a detailed map constructed by a project team of eight managers and accountants during a two day structured workshop; numerous unstructured interviews and observation of shop floor practices; document and archival analysis, and 140 photographs of the focal operation. Supplemented by extensive financial and operational data extracted from the firm’s accounting and MRP systems, including all data necessary to construct and implement bespoke capacity planning, work in progress (WIP) monitoring and simulation modelling tools. The case firm is anonymised.

Findings: The Lean manufacturing literature ignores the real-world issue of shared resources, and this gap is attributable to the concept of ‘rightsizing’ tools and equipment that is widely promoted within the Lean community. The case panel plant is characterised by extensive shared resources; many of which are also batch processes. The most appropriate pull-system method for this production environment is DBR. The detailed design of the DBR mechanism required a controlled transfer buffer of overhead conveyance capacity after the Drum because the extent of downstream process variability risked it being unable to offload panels, hence compromising throughput.

Research limitations/implications: The study is based upon a single case. This consequently has implications for the ability to generalise from the results.

Practical Implications: When the DBR pull-system design was implemented it reduced the number of panels in WIP by 60%. This equated to a 56% (18?days worth) reduction of manufacturing lead time and more than doubled the plant’s inventory turns (from 9.1 to 21.2). It also significantly improved delivery schedule adherence, with downstream jig stoppages in the Final Assembly falling from an average of six to less than one per week. The financial benefit was independently audited to equate to an annualised value of $850?K. Consequently, this project was awarded the first prize at its parent enterprise’s annual worldwide process improvement competition.

Originality/value: This paper details a novel technique that permits the routings of multiple value streams to be mapped and is useful for highlighting the identity and location of shared resources. It also contributes significantly to the literature that is available on the relationship between the Lean paradigm and the management of shared production resources, and adds to the literature on the detailed design and implementation of a DBR pull-system in a jobbing-type of environment.     

Comparative Capitalism without Capitalism,and Production without Workers: The Limits and Possibilities of Contemporary Institutional Analysis

The aim of this paper is to consider the extent to which the comparative capitalism literature fully reflects the available empirical evidence in its attempts to model different versions of capitalism and, in particular, whether it adequately captures the roles of diverse stakeholders within the capitalist system. In doing so, particular attention is accorded to the varieties of capitalism literature, business systems theory and regulation theory. In addition, there is reflection in the paper on whether any strand of the literature is able to deal effectively with the recent economic crisis and systemic change. It is argued that more attention needs to be devoted to exploring the structural causes of change and the marginalization of the interests of key social groupings, most notably workers, from the process of institutional redesign.