Assessing the Precision of Compositional Data in a Stratified Double Stage Cluster Sample: Application to the Swiss Earnings Structure Survey

Precision of released figures is not only an important quality feature of official statistics,it is also essential for a good understanding of the data. In this paper we show a casestudy of how precision could be conveyed if the multivariate nature of data has to betaken into account. In the official release of the Swiss earnings structure survey, the totalsalary is broken down into several wage components. We follow Aitchison's approachfor the analysis of compositional data, which is based on logratios of components. Wefirst present diferent multivariate analyses of the compositional data whereby the wagecomponents are broken down by economic activity classes. Then we propose a numberof ways to assess precision

Interactions between grain size and composition of sediments: two examples

Two contrasting case studies of sediment and detrital mineral composition are investigated in order to outline interactions between chemical composition and grain size. Modern glacial sediments exhibit a strong dependence of the two parameters due to the preferential enrichment of mafic minerals, especially biotite, in the fine-grained fractions. On the other hand, the composition of detrital heavy minerals (here: rutile) appears to be not systematically related to grain-size, but is strongly controlled by location, i.e. the petrology of the source rocks of detrital grains. This supports the use of rutile as a well-suited tracer mineral for provenance studies. The results further suggest that (i) interpretations derived from whole-rock sediment geochemistry should be flanked by grain-size observations, and (ii) a more sound statistical evaluation of these interactions require the development of new tailor-made statistical tools to deal with such so-called two-way compositions

Comparison studies of tin deposits (Priamurye, Russia) using the Aitchison’s methodology

A study of tin deposits from Priamurye (Russia) is performed to analyze the differencesbetween them based on their origin and also on commercial criteria. A particularanalysis based on their vertical zonality is also given for samples from Solnechnoedeposit. All the statistical analysis are made on the subcomposition formed by seventrace elements in cassiterite (In, Sc, Be, W, Nb, Ti and V) using the Aitchison’methodology of analysis of compositional data

Cap a una nova geografia regional? Notícia del seminari celebrat a la ciutat dels quatre rius

Del 28 al 30 de juny de 1989 se celebra a Girona el I Curs d'Estiu de Geografia, en el marc dels Cursos d'Estiu de l'Estudi General de Girona -Universidad Internacional Menéndez y Pelayo. La primera edició d'aquest curs es dedica a la geografia regional. Es tractava d'impulsar una discussió a fons sobre la revifalla del concepte de regió, observada no solament des d’algunes de les perspectives geogràfiques més innovadores, sinó també des d'altres camps de les ciències socials i humanes. Ens trobem davant d'una seriosa reconsideració teòrica i metodològica de la perspectiva regional, que inclou, alhora, una suggeridora reflexió sobre el paper que el lloc, el context espacial, té o hauria de tenir en l'explicació dels fenòmens socials, polítics i econòmics que afecten la nostra vida quotidiana. El text que segueix a continuació és una breu noticia de l’esmentat curs

Géopoint-82. Les territoires de la vie quotidienne

Relació i resum de les ponències del IV Col•loqui Geopoint 82, celebrat el maig d’aquell any a Avinyó on es van desenvolupar les ponències “Le territoire dans ses rapports avec les espaces géographiques: concept ancien, utilisation nouvelle.”, “Le Pays, niveau géographique.”, “Le territoire de la vie quotidienne et le référentiel-habitant.”, “Réseaux et niveaux de territorialité”, “Pratique de l'eco-développement.”, “Le territoire en milieu urbain.” i “La territorialité.”

El Bosc, element clau d'un paisatge i d'una comunitat

Aquest treball és un resum de la Memòria de Llicenciatura El Bosc, element clau d’un paisatge i d’una comunitat. La seva percepció per part dels pagesos de l’Alta Garrotxa. Assaig metodològic, llegida el 18 de desembre de 1981 a la Universitat Autònoma de Barcelona

Sobre geografía moral

Els geògrafs s’inclouen tant en el camp de les ciències de la terra com en el de les ciències socials, tot i que també es poden considerar filòsofs morals, perquè es preocupen i s’interessen pels valors, els costums i les aspiracions humanes de no només limitar-se a sobreviure, sinó també d’aconseguir una vida fructuosa i agradable. En aquest intent per aconseguir una bona vida, els éssers humans han hagut d’organitzar-se i servir-se del poder, amb el qual és fàcil, per altra banda, cometre abusos contra els més febles i també contra la natura. El vessant moral és inevitable en qualsevol detallada consideració de la realitat humana. Aquest article pretén explorar l’esmentat vessant en societats senzilles i complexes, és a dir, tant entre els pobles caçadors-recol·lectors com en aquelles cultures més sofisticades que han transformat el camp, el jardí i la ciutat

La Sociedad Geográfica de Madrid y el colonialismo español en Marruecos (1876-1956)

L’objectiu central de l’article és analitzar l’actitud que es manifestà a la Sociedad Geogràfica de Madrid en relació amb l’acció colonial espanyola al Marroc, des del 1876 —any de creació de la Societat— fins al 1956 —independència del Marroc i consegüent finalització del protectorat espanyol—. Així mateix, s’examinen les actuacions que dugué a terme per impulsar l’esmentat procés, els mecanismes que utilitzà per influir en la política exterior i en la societat espanyoles i les repercussions de la seva activitat

“El Mediterráneo en el diálogo Norte-Sur”: III Curso Internacional de Defensa. Jaca (Huesca), 19-23 de septiembre de 1995

Del 19 al 23 de setembre de 1995 es va celebrar a Jaca (Osca) el III Curs Internacional de Defensa, amb el títol específic “ El Mediterrani en el Diàleg Nord Sud”, organitzat per la Càtedra Miguel de Cervantes de l’Acadèmia General Militar i la Universitat de Saragossa. Els objectius assenyalats pels organitzadors es van centrar a potenciar l’intercanvi d’opinions entre especialistes i representants de les institucions sobre aspectes polítics, socials, econòmics i de defensa que afecten l’espai geopolític de les dues riberes del Mediterrani, i a analitzar els mecanismes de cooperació que actuen a l’àrea i la política de la Unió Europea a la zona

Inference of distributional parameters from compositional samples containing nondetects

Low concentrations of elements in geochemical analyses have the peculiarity of beingcompositional data and, for a given level of significance, are likely to be beyond thecapabilities of laboratories to distinguish between minute concentrations and completeabsence, thus preventing laboratories from reporting extremely low concentrations of theanalyte. Instead, what is reported is the detection limit, which is the minimumconcentration that conclusively differentiates between presence and absence of theelement. A spatially distributed exhaustive sample is employed in this study to generateunbiased sub-samples, which are further censored to observe the effect that differentdetection limits and sample sizes have on the inference of population distributionsstarting from geochemical analyses having specimens below detection limit (nondetects).The isometric logratio transformation is used to convert the compositional data in thesimplex to samples in real space, thus allowing the practitioner to properly borrow fromthe large source of statistical techniques valid only in real space. The bootstrap method isused to numerically investigate the reliability of inferring several distributionalparameters employing different forms of imputation for the censored data. The casestudy illustrates that, in general, best results are obtained when imputations are madeusing the distribution best fitting the readings above detection limit and exposes theproblems of other more widely used practices. When the sample is spatially correlated, itis necessary to combine the bootstrap with stochastic simulation

Tren d’alta velocitat i desenvolupament local urbà. Aportacions a una nova base teòrica

Una de les finalitats principals del tren d’alta velocitat és la d’aportar desenvolupament local en aquelles ciutats i territoris on se’n construeixi una estació. Per aquesta raó, calen reflexions teòriques que ajudin els agents i les institucions a planificar correctament l’arribada de la nova gran infraestructura de transport, especialment en els aspectes relacionats amb la capacitat d’organització dels actors territorials. La teoria reticular pot ser una base teòrica útil per evitar concepcions deterministes de la relació entre infraestructura i territori, per explicar com es produeix el procés de desenvolupament local i per demostrar la importància dels agents territorials en aquest procés

A compositional approach to stable isotope data analysis

Isotopic data are currently becoming an important source of information regardingsources, evolution and mixing processes of water in hydrogeologic systems. However, itis not clear how to treat with statistics the geochemical data and the isotopic datatogether. We propose to introduce the isotopic information as new parts, and applycompositional data analysis with the resulting increased composition. Results areequivalent to downscale the classical isotopic delta variables, because they are alreadyrelative (as needed in the compositional framework) and isotopic variations are almostalways very small. This methodology is illustrated and tested with the study of theLlobregat River Basin (Barcelona, NE Spain), where it is shown that, though verysmall, isotopic variations comp lement geochemical principal components, and help inthe better identification of pollution sources

Discrete and continuous compositions

This paper examines a dataset which is modeled well by thePoisson-Log Normal process and by this process mixed with LogNormal data, which are both turned into compositions. Thisgenerates compositional data that has zeros without any need forconditional models or assuming that there is missing or censoreddata that needs adjustment. It also enables us to model dependenceon covariates and within the composition

CODAPACK3D. A new version of Compositional Data Package

The statistical analysis of compositional data should be treated using logratios of parts,which are difficult to use correctly in standard statistical packages. For this reason afreeware package, named CoDaPack was created. This software implements most of thebasic statistical methods suitable for compositional data.In this paper we describe the new version of the package that now is calledCoDaPack3D. It is developed in Visual Basic for applications (associated with Excel©),Visual Basic and Open GL, and it is oriented towards users with a minimum knowledgeof computers with the aim at being simple and easy to use.This new version includes new graphical output in 2D and 3D. These outputs could bezoomed and, in 3D, rotated. Also a customization menu is included and outputs couldbe saved in jpeg format. Also this new version includes an interactive help and alldialog windows have been improved in order to facilitate its use.To use CoDaPack one has to access Excel© and introduce the data in a standardspreadsheet. These should be organized as a matrix where Excel© rows correspond tothe observations and columns to the parts. The user executes macros that returnnumerical or graphical results. There are two kinds of numerical results: new variablesand descriptive statistics, and both appear on the same sheet. Graphical output appearsin independent windows. In the present version there are 8 menus, with a total of 38submenus which, after some dialogue, directly call the corresponding macro. Thedialogues ask the user to input variables and further parameters needed, as well aswhere to put these results. The web site http://ima.udg.es/CoDaPack contains thisfreeware package and only Microsoft Excel© under Microsoft Windows© is required torun the software.Kew words: Compositional data Analysis, Software

Multivariate ARIMA Compositional Time Series Analysis

A compositional time series is obtained when a compositional data vector is observed atdifferent points in time. Inherently, then, a compositional time series is a multivariatetime series with important constraints on the variables observed at any instance in time.Although this type of data frequently occurs in situations of real practical interest, atrawl through the statistical literature reveals that research in the field is very much in itsinfancy and that many theoretical and empirical issues still remain to be addressed. Anyappropriate statistical methodology for the analysis of compositional time series musttake into account the constraints which are not allowed for by the usual statisticaltechniques available for analysing multivariate time series. One general approach toanalyzing compositional time series consists in the application of an initial transform tobreak the positive and unit sum constraints, followed by the analysis of the transformedtime series using multivariate ARIMA models. In this paper we discuss the use of theadditive log-ratio, centred log-ratio and isometric log-ratio transforms. We also presentresults from an empirical study designed to explore how the selection of the initialtransform affects subsequent multivariate ARIMA modelling as well as the quality ofthe forecasts