Pratique de l'heuristique de pente et le package CAPUSHE

National audienceLa mise en oeuvre des méthodes "data-driven" de calibration de critères pénalisés, issues de l'heuristique de pente de Birgé et Massart (2007), implique des difficultés pratiques

Slope Heuristics: Overview and Implementation

RR INRIA-7223, Version 1Model 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 (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

Slope heuristics for variable selection and clustering via Gaussian mixtures

Specific Gaussian mixtures are considered to solve simultaneously variable selection and clustering problems. A penalized likelihood criterion is proposed in Maugis and Michel (2008) to choose the number of mixture components and the relevant variable subset. This criterion is depending on unknown constants to be approximated in practical situations. A "slope heuristics" method is proposed and experimented to deal with this practical problem in this context. Numerical experiments on simulated datasets, a curve clustering example and a genomics application highlight the interest of the proposed heuristics

A non asymptotic penalized criterion for Gaussian mixture model selection

Specific Gaussian mixtures are considered to solve simultaneously variable selection and clustering problems. A non asymptotic penalized criterion is proposed to choose the number of mixture components and the relevant variable subset. Because of the non linearity of the associated Kullback-Leibler contrast on Gaussian mixtures, a general model selection theorem for MLE proposed by Massart (2007) is used to obtain the penalty function form. This theorem requires to control the bracketing entropy of Gaussian mixture families. The ordered and non-ordered variable selection cases are both addressed in this paper

Strengthening Integrated Primary Health Care in Sofala, Mozambique

Background: Large increases in health sector investment and policies favoring upgrading and expanding the public sector health network have prioritized maternal and child health in Mozambique and, over the past decade, Mozambique has achieved substantial improvements in maternal and child health indicators. Over this same period, the government of Mozambique has continued to decentralize the management of public sector resources to the district level, including in the health sector, with the aim of bringing decision-making and resources closer to service beneficiaries. Weak district level management capacity has hindered the decentralization process, and building this capacity is an important link to ensure that resources translate to improved service delivery and further improvements in population health. A consortium of the Ministry of Health, Health Alliance International, Eduardo Mondlane University, and the University of Washington are implementing a health systems strengthening model in Sofala Province, central Mozambique.Description of implementation: The Mozambique Population Health Implementation and Training (PHIT) Partnership focuses on improving the quality of routine data and its use through appropriate tools to facilitate decision making by health system managers; strengthening management and planning capacity and funding district health plans; and building capacity for operations research to guide system-strengthening efforts. This seven-year effort covers all 13 districts and 146 health facilities in Sofala Province.Evaluation design: A quasi-experimental controlled time-series design will be used to assess the overall impact of the partnership strategy on under-5 mortality by examining changes in mortality pre- and post-implementation in Sofala Province compared with neighboring Manica Province. The evaluation will compare a broad range of input, process, output, and outcome variables to strengthen the plausibility that the partnership strategy led to healthsystem improvements and subsequent population health impact.Discussion: The Mozambique PHIT Partnership expects to provide evidence on the effect of efforts to improvedata quality coupled with the introduction of tools, training, and supervision to improve evidence-based decision making. This contribution to the knowledge base on what works to enhance health systems is highly replicable for rapid scale-up to other provinces in Mozambique, as well as other sub-Saharan African countries with limitedresources and a commitment to comprehensive primary health care

Mobility to and from, around and about Brussels

Observations Preliminary observation: a knowledge base that needs improvement A large number of observations and forecasts on which the Brussels-Capital Region (BCR) bases its mobility policy arise from a vision focused on the “transportation” of passengers and goods from a point A to a point B, and rely on data that are often insufficient or on questionable hypotheses. This vision, moreover, does not adequately consider a more global approach to mobility – in particular one that integrates t..