Search results for "proPO"
showing 10 items of 1325 documents
Regression models for multivariate ordered responses via the Plackett distribution
2008
AbstractWe investigate the properties of a class of discrete multivariate distributions whose univariate marginals have ordered categories, all the bivariate marginals, like in the Plackett distribution, have log-odds ratios which do not depend on cut points and all higher-order interactions are constrained to 0. We show that this class of distributions may be interpreted as a discretized version of a multivariate continuous distribution having univariate logistic marginals. Convenient features of this class relative to the class of ordered probit models (the discretized version of the multivariate normal) are highlighted. Relevant properties of this distribution like quadratic log-linear e…
On statistical inference for the random set generated Cox process with set-marking.
2007
Cox point process is a process class for hierarchical modelling of systems of non-interacting points in ℝd under environmental heterogeneity which is modelled through a random intensity function. In this work a class of Cox processes is suggested where the random intensity is generated by a random closed set. Such heterogeneity appears for example in forestry where silvicultural treatments like harvesting and site-preparation create geometrical patterns for tree density variation in two different phases. In this paper the second order property, important both in data analysis and in the context of spatial sampling, is derived. The usefulness of the random set generated Cox process is highly…
Comment on ‘Generating survival times to simulate Cox proportional hazards models with time-varying covariates’
2013
IndElec: A Software for Analyzing Party Systems and Electoral Systems
2011
IndElec is a software addressed to compute a wide range of indices from electoral data, which are intended to analyze both party systems and electoral systems in political studies. Further, IndElec can calculate such indices from electoral data at several levels of aggregation, even when the acronyms of some political parties change across districts. As the amount of information provided by IndElec may be considerable, this software also aids the user in the analysis of electoral data through three capabilities. First, IndElec automatically elaborates preliminary descriptive statistical reports of computed indices. Second, IndElec saves the computed information into text files in data matri…
Segmented relationships to model erosion of regression effect in Cox regression
2010
In this article we propose a parsimonious parameterisation to model the so-called erosion of the covariate effect in the Cox model, namely a covariate effect approaching to zero as the follow-up time increases. The proposed parameterisation is based on the segmented relationship where proper constraints are set to accomodate for the erosion. Relevant hypothesis testing is discussed. The approach is illustrated on two historical datasets in the survival analysis literature, and some simulation studies are presented to show how the proposed framework leads to a test for a global effect with good power as compared with alternative procedures. Finally, possible generalisations are also present…
A comparison of semiparametric approaches to evaluate composite endpoints in heart failure trials
2021
In heart failure trials efficacy is usually proven by a composite endpoint including cardiovascular death (CVD) and recurrent heart failure hospitalisations (HFH), evaluated with time-to-first-event analysis based on a Cox model. As a considerable fraction of events is ignored that way, recurrent event[for full text, please go to the a.m. URL]
Flexible latent trait aggregation to analyze employability after the Ph.D. in Italy
2015
The analysis of satisfaction, employability and economic perspectives after the Ph.D. in Italy has not received adequate attention in the past, especially in terms of comparison among universities. To analyze these aspects, in this paper we consider data from the survey ‘Statistica in TEma di Laureati e LAvoro’ on doctors who achieved the title on 2007, 2008 and 2009 [CILEA, Laureati STELLA, indagine occupazionale post-dottorato, dottori di ricerca 2007–2008, Tech. Rep., CILEA, Segrate, 2010; CILEA,Laureati STELLA, indagine occupazionale post-dottorato, dottori di ricerca 2008–2009, Tech. Rep., CILEA, Segrate, 2011]. To deal with the complex, multidimensional nature of the concept, we propo…
Electrochemical and DFT studies of the oxidative decomposition of the trihydride complexes Cp*M(dppe)H3 (M = Mo, W) in acetonitrile
2006
International audience; A detailed electrochemical study of the oxidative decomposition of the trihydride complexes Cp*M(dppe)H3 (M = Mo, W) in acetonitrile is presented. For the Mo complex, the decomposition occurs by four different pathways involving classical and non-classical tautomers, whereas only the classical form is accessible for the W derivative. Each of the decomposition pathways has been quantitatively assessed by analyses of the linear sweep voltammograms. In addition to the previously established (B. Pleune, D. Morales, R. Meunier-Prest, P. Richard, E. Collange, J. C. Fettinger and R. Poli, J. Am. Chem. Soc., 1999, 121, 2209–2225) deprotonation, disproportionation, and H2 red…
Logic for accumulation of design science research theory
2014
The paper introduces a structured logic for iterative and incremental accumulation of a design theory during a research project and across research programs. The logic is proposed to help researchers understand the links between parallel search spaces related to a particular design and linking to theoretical knowledge bases produced by previous search processes. The proposition rests on the notion that representing the structure and logic of design science research (DSR) theory using CIMO enables the elements of the knowledge base to be more easily evaluated, combined, and transferred between related search spaces. We view DSR theory development as an iterative and incremental social proces…
Quasivarieties of Algebras
2001
This chapter plays a twofold role in the book. Firstly, the chapter surveys basic facts about quasivarieties of algebras. These facts are widely utilised in the subsequent chapters devoted to algebraizable logics. Secondly, the chapter shows how the methods initially elaborated for protoalgebraic sentential logics in the first part can be also applied in the area of equational logic. Most of the results presented in this chapter are proved by way of adapting the purely consequential methods of sentential logic to the needs of the (quasi) equational systems associated with quasivarieties of algebras.