Marie Piron

Bio: Marie Piron is an academic researcher from Institut de recherche pour le développement. The author has contributed to research in topics: Population. The author has an hindex of 7, co-authored 20 publications receiving 1156 citations.

Statistique exploratoire multidimensionnelle

Abstract: Ouvragedestine aux etudiants de 2e cycle Sommaire: METHODES FACTORIELLES: Analyse generale, decomposition aux valeurs singulieres; Analyse en Composantes Principales; Analyse des correspondances; Analyse des correspondances multiples; QUELQUES METHODES DE CLASSIFICATION: Agregation autour des centres mobiles; Classification hierarchique; Classification mixte et description statistique des classes; Complementarite entre analyse factorielle et classificationLIENS AVEC LES METHODES EXPLICATIVES USUELLES, METHODES DERIVEES: Analyse canonique; Regression multiple, modele lineaire; Analyse factorielle discriminante; Modeles log-lineaires; Segmentation; Structures de graphe, analyses locales; Tableaux multiples, groupes de variables VALIDITE ET PORTEE DES RESULTATS: Signification des valeurs propres et des taux d'inertie; Stabilite des axes, des formes, des classes

Utilisation de typologies multi-dates pour l’analyse des transformations socio-spatiales de Bogota (Colombie)

Abstract: A l’image de nombreuses autres villes du Sud, la capitale de la Colombie, Bogota, est entree depuis une vingtaine d’annees dans une nouvelle phase de developpement, moins rapide : la dynamique d’expansion peripherique a cede la place a une dynamique dominee par la redistribution des populations dans l’espace urbain. Cet article a pour objectif d’analyser l’evolution et les transformations des grandes formes de la configuration socio-spatiale de Bogota sur la periode de 1973 a 1993. Pour cela, nous mettons en place une typologie « multi-dates » concue de facon a rendre compte des structures perennes de la composition socio-demographique de Bogota. La methodologie proposee consiste a definir un univers de reference coherent qui est l’ensemble des menages recenses en 1973 et en 1993 et a travailler sur des variables socio-demographiques de base sur les menages qui sont des informations factuelles reconnues. L’utilisation de l’analyse typologique (analyse factorielle et classification) permet, dans ces conditions, d’eprouver et de produire des structures fortes et stables de la population de Bogota. Cette analyse multidates produit un indicateur multivarie de la composition sociale de Bogota, qui permet d’adopter une approche globale pour etudier les trajectoires des arrondissements dans la structure sociale de la ville.

Mobilités quotidiennes et inégalités socio-territoriales à Bogotá, Santiago du Chili et São Paulo

Abstract: La question du role des mobilites quotidiennes comme facteur d’inegalites socio-spatiales se pose avec une grande acuite en Amerique latine, du fait des caracteristiques de l’urbanisation sur ce continent : une transition urbaine bien avancee, des metropoles « millionnaires » tres etalees et peu denses, marquees par de profondes inegalites sociales, une tres forte segregation socio-residentielle, ainsi qu’une inequitable repartition des emplois dans la ville. L’objectif est d’explorer ici le lien entre les deplacements domicile-travail et les inegalites socio-spatiales dans trois metropoles contrastees (Bogota, Santiago, Sao Paulo). Nous montrons qu’au-dela du simple effet de la hierarchie sociale, l’effet territorial est determinant sur les conditions de mobilite quotidienne des citadins.

Expansion de l'agglomération de Lima et différenciation de l’espace résidentiel : analyse exploratoire d’un corpus de données diversifié

Abstract: Lima presente des formes de differenciation socio-spatiale en grande partie conformes au modele des metropoles andines avec, d'une part une opposition entre un ensemble de quartiers centraux occupes par les classes moyennes ou aisees et des quartiers peripheriques plus recents et beaucoup plus populaires, d'autre part l'expansion de quartiers de standing dans une direction privilegiee, en l'occurrence a l'est des quartiers centraux. Ce modele est encore tres pregnant mais semble etre modifie depuis la fin du siecle dernier par des phenomenes de diversification interne d’ensembles naguere plus homogenes. Notre objectif est de proposer une demarche exploratoire pour comprendre l'organisation spatiale actuelle de la differenciation sociale a Lima. Sur la base des donnees du dernier recensement national de la population en 2007 et d'un ensemble de photographies aeriennes et d'images satellite prises au cours de la deuxieme moitie du 20e siecle, nous elaborons, a l'echelon de l'ilot, des indicateurs cartographiques et statistiques des strates successives de l'expansion de Lima et de son actuelle structure socio-spatiale. Il en ressort, dans un premier temps, que l’agglomeration s’organise selon une echelle d'integration sociale et urbaine qui s'inscrit spatialement sur un gradient, depuis le centre vers les peripheries, en lien avec la periode d’apparition des ensembles d’ilots. Puis, dans un second temps, une serie d'analyses statistiques multidimensionnelles reintroduisant visuellement l'ilot permettent de nuancer cette conclusion par l'etude de la variabilite interne aux strates d'expansion. Il est ainsi possible de saisir les dynamiques territoriales en cours et de poser l’hypothese d’une reorganisation de la structure opposant le centre aux peripheries.

Inégalités d’accès aux ressources de la ville analysées à l’aide des mobilités quotidiennes : approche méthodologique exploratoire à São Paulo

Abstract: Cet article, avant tout methodologique, explore la dispersion spatiale des lieux d’activite (etude et travail) frequentes au quotidien par des individus au regard de leurs caracteristiques sociodemographiques et de leur lieu de residence, dans l’agglomeration de Sao Paulo. L’etude repose sur l’exploitation de donnees d’enquetes sur les systemes de mobilites realisees aupres d’un echantillon de menages. L’accent est mis sur la demarche qui fait intervenir une serie d’analyses centrographiques que l’on combine dans un deuxieme temps a une analyse typologique. Nous montrons l’interet de recourir a ces outils pour apprehender et visualiser les inegalites d’acces aux ressources urbaines en lien avec le cycle de vie des individus, la hierarchie sociale et le lieu de residence.

FactoMineR: An R Package for Multivariate Analysis

Abstract: In this article, we present FactoMineR an R package dedicated to multivariate data analysis. The main features of this package is the possibility to take into account different types of variables (quantitative or categorical), different types of structure on the data (a partition on the variables, a hierarchy on the variables, a partition on the individuals) and finally supplementary information (supplementary individuals and variables). Moreover, the dimensions issued from the different exploratory data analyses can be automatically described by quantitative and/or categorical variables. Numerous graphics are also available with various options. Finally, a graphical user interface is implemented within the Rcmdr environment in order to propose an user friendly package.

NbClust: An R Package for Determining the Relevant Number of Clusters in a Data Set

Abstract: Clustering is the partitioning of a set of objects into groups (clusters) so that objects within a group are more similar to each others than objects in different groups. Most of the clustering algorithms depend on some assumptions in order to define the subgroups present in a data set. As a consequence, the resulting clustering scheme requires some sort of evaluation as regards its validity. The evaluation procedure has to tackle difficult problems such as the quality of clusters, the degree with which a clustering scheme fits a specific data set and the optimal number of clusters in a partitioning. In the literature, a wide variety of indices have been proposed to find the optimal number of clusters in a partitioning of a data set during the clustering process. However, for most of indices proposed in the literature, programs are unavailable to test these indices and compare them. The R package NbClust has been developed for that purpose. It provides 30 indices which determine the number of clusters in a data set and it offers also the best clustering scheme from different results to the user. In addition, it provides a function to perform k-means and hierarchical clustering with different distance measures and aggregation methods. Any combination of validation indices and clustering methods can be requested in a single function call. This enables the user to simultaneously evaluate several clustering schemes while varying the number of clusters, to help determining the most appropriate number of clusters for the data set of interest.

The Diversity of Modern Capitalism

Abstract: This book considers why institutional forms of modern capitalist economies differ internationally, and proposes a typology of capitalism based on the theory of institutional complementarity Different economic models are not simply characterized by different institutional forms, but also by particular patterns of interaction between complementary institutions which are the core characteristics of these models Institutions are not just simply devices which would be chosen by 'social engineers' in order to perform a function as efficiently as possible; they are the outcome of a political economy process Therefore, institutional change should be envisaged not as a move towards a hypothetical 'one best way', but as a result of socio-political compromises Based on a theory of institutions and comparative capitalism, the book proposes an analysis of the diversity of modern economies - from America to Korea - and identifies five different models: the market-based Anglo-Saxon model; Asian capitalism; the Continental European model; the social democratic economies; and the Mediterranean model Each of these types of capitalism is characterized by specific institutional complementarities The question of the stability of the Continental European model of capitalism has been open since the beginning of the 1990s: inferior macroeconomic performance compared to Anglo-Saxon economies, alleged unsustainability of its welfare systems, too rigid markets, etc The book examines the institutional transformations that have taken place within Continental European economies and analyses the political project behind the attempts at transforming the Continental model It argues that Continental European economies will most likely stay very different from the market-based economies, and caat political strategies promoting institutional change aiming at convergence with the Anglo-Saxon model are bound to meet considerable opposition

A user's guide to functional diversity indices

Abstract: Functional diversity is the diversity of species traits in ecosystems. This concept is increasingly used in ecological research, yet its formal definition and measurements are currently under discussion. As the overall behavior and consistency of functional diversity indices have not been described so far, the novice user risks choosing an inaccurate index or a set of redundant indices to represent functional diversity. In our study we closely examine functional diversity indices to clarify their accuracy, consistency, and independence. Following current theory, we categorize them into functional richness, evenness, or divergence indices. We considered existing indices as well as new indices developed in this study. The new indices aimed at remedying the weaknesses of currently used indices (e.g., by taking into account intraspecific variability). Using virtual data sets, we test (1) whether indices respond to community changes as expected from their category and (2) whether the indices within each category are consistent and independent of indices from other categories. We also test the accuracy of methods proposed for the use of categorical traits. Most classical functional richness indices either failed to describe functional richness or were correlated with functional divergence indices. We therefore recommend using the new functional richness indices that consider intraspecific variability and thus empty space in the functional niche space. In contrast, most functional evenness and divergence indices performed well with respect to all proposed tests. For categorical variables, we do not recommend blending discrete and real-valued traits (except for indices based on distance measures) since functional evenness and divergence have no transposable meaning for discrete traits. Nonetheless, species diversity indices can be applied to categorical traits (using trait levels instead of species) in order to describe functional richness and equitability.

Computer simulations in physics teaching and learning: a case study on students' understanding of trajectory motion

Abstract: A major research domain in physics education is focused on the study of the effects of various types of teaching interventions aimed to help students' alternative conceptions transformation Computer simulations are applications of special interest in physics teaching because they can support powerful modeling environments involving physics concepts and processes In this study two groups (control and experimental) of 15–16 years old students were studied to determine the role of computer simulations in the development of functional understanding of the concepts of velocity and acceleration in projectile motions Both groups received traditional classroom instruction on these topics; the experimental group used computer simulations also The results presented here show that students working with simulations exhibited significantly higher scores in the research tasks Our findings strongly support that computer simulations may be used as an alternative instructional tool, in order to help students confront their cognitive constraints and develop functional understanding of physics