The exact properties of the lawless and wang operational ridge regression estimator in a misspecified regression equation

The exact properties of the Lawless and Wang Operational Ridge Regression estimator are derived in the context of a misspecified regression equation.     

An algorithm to compute the cdf of the product of two normal random variables

This paper provides a fortran algorithm that can be used to compute the cdf of the product of two normal distribution random variables. We also give references that provide mathematical properties, tables, and applications of this distribution     

Diagnostic tools in generalized Weibull linear regression models

We propose some statistical tools for diagnosing the class of generalized Weibull linear regression models [A.A. Prudente and G.M. Cordeiro, Generalized Weibull linear models, Comm. Statist. Theory Methods 39 (2010), pp. 3739–3755]. This class of models is an alternative means of analysing positive, continuous and skewed data and, due to its statistical properties, is very competitive with gamma regression models. First, we show that the Weibull model induces ma-ximum likelihood estimators asymptotically more efficient than the gamma model. Standardized residuals are defined, and their statistical properties are examined empirically. Some measures are derived based on the case-deletion model, including the generalized Cook's distance and measures for identifying influential observations on partial F-tests. The results of a simulation study conducted to assess behaviour of the global influence approach are also presented. Further, we perform a local influence analysis under the case-weights, response and explanatory variables perturbation schemes. The Weibull, gamma and other Weibull-type regression models are fitted into three data sets to illustrate the proposed diagnostic tools. Statistical analyses indicate that the Weibull model fitted into these data yields better fits than other common alternative models.     

Linking Disconnected Spaces or Venue Shopping? Trade-Offs in Participatory Opportunities in the EU

This article discusses why national civil society organisations (CSOs) use or abstain to use the participatory opportunities that the EU has developed in the last years. This is done by analysing the role of French and Spanish civil society groups in the debates on participatory democracy during the drafting and the referendum debates of the European Constitution (2002–2005). The paper departs from existing assessments of the role of national civil society in the Convention and demonstrates that national organisations built on their expertise on certain EU policies, on access to EU-level political actors and on contacts and alliances with other CSOs. It also differs from previous studies in finding that participation does not entail sharing the interpretive frame promoted by the EU. The finding that access opportunities do not fundamentally influence the frames of the organisations is related to their ability to strategically choose to participate in European and national venues. The paper finds that because of their scepticism on the constitution's participatory framing, French organisations preferred a stronger role at the national level, whereas Spanish organisations did not have real incentives to develop a campaign at the national level. While it is expected that dialogue with CSOs can contribute to bridging the gap between the EU and its citizens, this paper finds that the institutional setting provided incentives for national organisations to get involved only in one of the levels rather than to link them.     

A Stochastic Model to Assess the Effect of Meat Inspection Practices on the Contamination of the Pig Carcasses

The objective of meat inspection is to promote animal and public health by preventing, detecting, and controlling hazards originating from animals. With the improvements of sanitary level in pig herds, the hazards profile has shifted and the inspection procedures no longer target major foodborne pathogens (i.e., not risk based). Additionally, carcass manipulations performed when searching for macroscopic lesions can lead to cross‐contamination. We therefore developed a stochastic model to quantitatively describe cross‐contamination when consecutive carcasses are submitted to classic inspection procedures. The microbial hazard used to illustrate the model was Salmonella, the data set was obtained from Brazilian slaughterhouses, and some simplifying assumptions were made. The model predicted that due to cross‐contamination during inspection, the prevalence of contaminated carcass surfaces increased from 1.2% to 95.7%, whereas the mean contamination on contaminated surfaces decreased from 1 logCFU/cm² to ?0.87 logCFU/cm², and the standard deviations decreased from 0.65 to 0.19. These results are explained by the fact that, due to carcass manipulations with hands, knives, and hooks, including the cutting of contaminated lymph nodes, Salmonella is transferred to previously uncontaminated carcasses, but in small quantities. These small quantities can easily go undetected during sampling. Sensitivity analyses gave insight into the model performance and showed that the touching and cutting of lymph nodes during inspection can be an important source of carcass contamination. The model can serve as a tool to support discussions on the modernization of pig carcass inspection.     

Dynamic evolution of alliance portfolios

This research advances in the conceptualization and the operationalization of the factors or microdynamics that determine the choice of partners. Most of the literature in this area of research has centered on the individual alliance without taking into account the set of alliances that a firm makes. This research applies a holistic approach, analyzing the set of alliances as a whole and points to the factors related to alliance portfolios that affect the choice of partners. The authors propose a longitudinal model that allows us to analyze the evolution of interorganizational networks. A Simulation Investigation for Empirical Network Analysis (SIENA) has been applied to a sample of 229 firms, analyzing 10,556 strategic alliances established between them over a 12 year period. The results show that certain factors over which managers exercise a degree of control (deliberate endogenous microdynamics) exert significant influences on the choice of partners by the focal actor and thereby on the dynamic configuration of alliance portfolios.     

Applying kaizen to the schedule in a concurrent environment

Not only ETO (Engineering to Order), but even serial production industry should know how to deal with projects and their schedule: plant commissioning, shutdown, introducing new products and similar circumstances should be managed with adequate planning and resource allocation techniques to create a schedule useful in decision making during the execution. The current complex reality, with evolving technologies and fierce pressure to reach the market as soon as possible, pushes the project managers to use more advanced techniques than waterfall planning, such as agile or lean. It also requires them to take a holistic view and manage concurrent tasks in complex projects. The contributions of this paper are two: the proposal to control specific parallel groups of waterfall activities under uncertain environments, which can lead to iterations and reworks, as a single concurrent Activity Managed by Kanban Methods (AMKM). This activity can be subsequently embedded into traditional scheduling approaches as CPM-PERT. The second contribution is the feasibility of its application in industrial environments due to the affordability of simulation software. Two use cases are shown as evidence. It is not a disruptive proposal, but a kaizen action based on very mature technologies. Finally, it is suggested some improvements to be implemented in Project Management Software due to this ‘kaizen’ proposal.     

Measuring operational excellence: an operational excellence profitability (OEP) approach

The pursuit of operational excellence in the manufacturing industry is at rise but its measurement still lacks of appropriate indicators to determine its financial benefits. The ambiguity is due to the impact arisen from manufacturing fluctuations such as price and cost, production mix and direct and indirect parameters variations. Manufacturing fluctuations distort the cost benefit of operational excellence. This paper, therefore, proposes the OEP (Operational Excellence Profitability) indicators to isolate the impact of manufacturing fluctuation and distinctly identify the payback of operational excellence strategies and initiatives through cost benefits of achieving higher efficiency and yield. The paper presents the conceptual and mathematical development of the proposed OEP indicators and the formulas used for their calculation. Hypothetical and industrial-based investigations and applications of the OEP indicators are conducted for their validation. The results obtained from the hypothetical exercise and industrial case suggest that OEP indicators can provide an effective cost-benefit analysis of operational excellence. This would contribute in providing manufacturing organizations with more complete information regarding the performance of their processes, which will allow their directors and managers to take better decisions related to the management and improvement of their processes.     

Methodology for the Calculation of Annualized Incremental Risks in Systems of Dams

In the past few years, the field of dam safety has approached risk informed methodologies throughout the world and several methodologies and programs are appearing to aid in the systematization of the calculations. The most common way of implementing these calculations is through the use of event trees, computing event probabilities, and incremental consequences. This methodology is flexible enough for several situations, but its generalization to the case of systems of several dams is complex and its implementation in a completely general calculation methodology presents some problems. Retaining the event tree framework, a new methodology is proposed to calculate incremental risks. The main advantage of this proposed methodology is the ease with which it can be applied to systems of several dams: with a single risk model that describes the complete system and with a single calculation the incremental risks of the system can be obtained, being able to allocate the risk of each dam and of each failure mode. The article shows how both methodologies are equivalent and also applies them to a case study.