Slope heuristics: overview and implementation

Model selection is a general paradigm which includes many statistical problems. One of the most fruitful and popular approaches to carry it out is the minimization of a penalized criterion. Birgé and Massart (Probab. Theory Relat. Fields 138:33–73, 2006) have proposed a promising data-driven method to calibrate such criteria whose penalties are known up to a multiplicative factor: the “slope heuristics”. Theoretical works validate this heuristic method in some situations and several papers report a promising practical behavior in various frameworks. The purpose of this work is twofold. First, an introduction to the slope heuristics and an overview of the theoretical and practical results about it are presented. Second, we focus on the practical difficulties occurring for applying the slope heuristics. A new practical approach is carried out and compared to the standard dimension jump method. All the practical solutions discussed in this paper in different frameworks are implemented and brought together in a Matlab graphical user interface called capushe. Supplemental Materials containing further information and an additional application, the capushe package and the datasets presented in this paper, are available on the journal Web site.     

Lean-healthcare approach to reduce costs in a sterilization plant based on surgical tray rationalization

Abstract

Sterilization plants process all reusable materials used in hospitals during different stages of healthcare provision. Most items sterilized come from the surgical theater in the form of individual instruments, linen and surgical trays. Reducing the number of instruments in trays impacts on the performance of the sterilization process. Here, we propose a three-phase method, based on lean healthcare principles, cluster analysis and kaizen groups of experts to rationalize surgical trays, reducing sterilization processing costs. We innovate by proposing a strategy to approach tray rationalization prioritizing surgical specialties that are both complex and frequent, and by using group technology to cluster surgical trays expediting expert analyses carried out by kaizen groups. Our propositions were tested in a high complexity, tertiary care hospital, covering 12 surgical specialties, reducing the number of instruments by average 9.75%, and the time-to-assemble trays by average 9.68%, obtaining annual savings of US$285.756,00 in sterilization processing costs.     

Hazardous journey in intimacy: HIV transmission risk behaviors of young men who are victims of past sexual abuses and who have sexual relations with men

The aim of this research was to explore the behavioral patterns and dynamics that may increase vulnerability towards HIV transmission among young men who have been sexually molested as children and who have sexual relations with men. In recent years, researchers have found that a larger number of gay or bisexual men have been sexually abused as children than other men. In this study, we wanted to explore the possible links between sexual victimization of young men and risky sexual behaviors related to HIV transmission among these men.     

Functional approaches for predicting land use with the temporal evolution of coarse resolution remote sensing data

The sensor SPOT 4/Végétation gives every day satellite images of Europe with medium spatial resolution, each pixel corresponding to an area of 1 r km 2 1 r km. Such data are useful to characterize the development of the vegetation at a large scale. The pixels, named "mixed' pixels, aggregate information of different crops and thus different themes of interest (wheat, corn, forest, …). We aim at estimating the land use when observing the temporal evolution of reflectances of mixed pixels. The statistical problem is to predict proportions with longitudinal covariates. We compared two functional approaches. The first relies on varying-time regression models and the second is an extension of the multilogit model for functional data. The comparison is achieved on a small area on which the land use is known. Satellite data were collected between March and August 1998. The functional multilogit model gives better predictions and the use of composite vegetation index is more efficient.     

Use of videotape feedback with severely disturbed adolescents.

A year of group therapy using videotape feedback with seriously disturbed adolescents offers evidence that such feedback facilitates the correction of these youngsters' distorted body images, low self-esteem, lack of capacity for self-observation, and poor peer relationships. The conscious use of videotape also played an integral part in the group process. It seemed to serve as a third therapist, with considerable amounts of resistance and transference focused on the equipment as it went through the process of being monster, toy and useful tool. An additional benefit was provided to the cotherapists in terms of supervision, and in teaching other staff the techniques of group therapy.     

Separable Preferences,Strategyproofness, and Decomposability

We consider strategyproof social choice functions defined over product domains. If preferences are strict orderings and separable, then strategyproof social choice functions must be decomposable provided that the domain of preferences is rich. We provide several characterization results in the case where preferences are separable only with respect to the elements of some partition of the set of components and these partitions vary across individuals. We characterize the libertarian social choice function and show that no superset of the tops separable domain admits strategyproof nondictatorial social choice functions.     

A Latent Class Binomial Logit Methodology for the Analysis of Paired Comparison Choice Data

A latent class model for identifying classes of subjects in paired comparison choice experiments is developed. The model simultaneously estimates a probabilistic classification of subjects and the logit models' coefficients relating characteristics of objects to choices for each respective group among two alternatives in paired comparison experiments. A modest Monte Carlo analysis of algorithm performance is presented. The proposed model is illustrated with empirical data from a consumer psychology experiment that examines the determinants of perceived consumer risk. The predictive validity of the method is assessed and compared to that of several other procedures. The sensitivity of the method to (randomly) eliminate comparisons, which is important in view of reducing respondent fatigue in the task, is investigated.     

RANKING ECONOMICS DEPARTMENTS IN EUROPE: A STATISTICAL APPROACH

We provide a ranking of economics departments in Europe and we discuss the methods used to obtain it. The JEL CD‐ROM serves as a database for a period covering ten years. Journals are ranked using a combination of expert opinions and citation data to produce a scale from 1 to 10. The publication output and habits of fifteen European countries plus California are then compared. Individuals with a contribution greater than a predetermined minimum level are regrouped into departments which are ranked according to their total scores. A standard deviation is provided to underline the uncertainty of this ranking. (JEL: I29, D63, C12, C14)     

Active participation in preventionist professional practices: a specific ergonomics training course

Currently, the different forms of corporate management methods (quality circles, lean manufacturing, etc.) are usually based on employee mobilisation. Very often, the goal of this type of approach is at best, to ensure that employees embrace corporate projects, or otherwise to impose changes on them without taking into account the real work and difficulties that they face daily. However, do these employee solicitation methods converge with participatory approaches as envisaged by ergonomists and more generally, preventionists? Based on the observation that the activity of institutional preventionists evolves with regulatory constraints and work related to the monitoring of indicators, the implementation and steering of the participatory approach within companies may be a major lever for prevention. After describing the foundations of a participatory approach, this paper will present a training experiment aimed at implementing and promoting employee participation in prevention efforts. The content of this training is then analysed with regard to the balance between methodology and the use of trainees' narratives. The results of the training session are presented from the point of view of the development prospects for pedagogical tools and the organisation of the training.     

Ergonomics at Volkswagen Brasil. Multidisciplinary work to equalize health, productivity and quality

Following the technological developments and presented to the multidisciplinary processes as automakers, Volkswagen Brazil, represented by its ergonomists, through this paper, shows the importance of ergonomic efficiency of management applied to various levels of life of a product, since its creation to its final implementation on production lines.The preventive work of ergonomists during the processes leading to production of a vehicle is accomplished through assessments on a simulated system called the Digital Factory. Since the initial stages to final product delivery there is a need for a multidisciplinary aligning the concepts of ergonomics, productivity and quality of product. Industrial Engineering, Process Engineering, ergonomists and workers are involved in the analysis made through the Workshop's showing the importance of discussion between the various users of the systems. The processes of series are also equipped with a set of certifications flow of job and planned audits on items that describe processes and applied ergonomics.