Search results for "estadística"
showing 10 items of 196 documents
Dynamic-Interactive Graphics for Statistics (26 years later)
2014
This paper briefly reviews the history of dynamic-interactive graphicsfor statistics, introduces an example of such graphics, and provides a fewglimpses as to the current state of things and the future trends we envision.The general conclusion is that dynamic-interactive graphics for statistics arethriving more than ever as they shift from the desktop to the internet. Thus,dynamic-interactive graphics are becoming increasingly important as they: 1) provide non-experts in statistics with the means to carry out analyses on their own; and 2) teach the basic concepts of statistics to students and practitioners with low to moderate mathematics skills. Their increasingpopularity makes the lesson…
Bayesian joint ordinal and survival modeling for breast cancer risk assessment
2016
We propose a joint model to analyze the structure and intensity of the association between longitudinal measurements of an ordinal marker and time to a relevant event. The longitudinal process is defined in terms of a proportional-odds cumulative logit model. Time-to-event is modeled through a left-truncated proportionalhazards model, which incorporates information of the longitudinal marker as well as baseline covariates. Both longitudinal and survival processes are connected by means of a common vector of random effects. General inferences are discussed under the Bayesian approach and include the posterior distribution of the probabilities associated to each longitudinal category and the …
On the convenience of heteroscedasticity in highly multivariate disease mapping
2019
Highly multivariate disease mapping has recently been proposed as an enhancement of traditional multivariate studies, making it possible to perform the joint analysis of a large number of diseases. This line of research has an important potential since it integrates the information of many diseases into a single model yielding richer and more accurate risk maps. In this paper we show how some of the proposals already put forward in this area display some particular problems when applied to small regions of study. Specifically, the homoscedasticity of these proposals may produce evident misfits and distorted risk maps. In this paper we propose two new models to deal with the variance-adaptiv…
Bayesian analysis of a disability model for lung cancer survival
2016
Bayesian reasoning, survival analysis and multi-state models are used to assess survival times for Stage IV non-small-cell lung cancer patients and the evolution of the disease over time. Bayesian estimation is done using minimum informative priors for the Weibull regression survival model, leading to an automatic inferential procedure. Markov chain Monte Carlo methods have been used for approximating posterior distributions and the Bayesian information criterion has been considered for covariate selection. In particular, the posterior distribution of the transition probabilities, resulting from the multi-state model, constitutes a very interesting tool which could be useful to help oncolog…
Some links between conditional and coregionalized multivariate Gaussian Markov random fields
2020
Abstract Multivariate disease mapping models are attracting considerable attention. Many modeling proposals have been made in this area, which could be grouped into three large sets: coregionalization, multivariate conditional and univariate conditional models. In this work we establish some links between these three groups of proposals. Specifically, we explore the equivalence between the two conditional approaches and show that an important class of coregionalization models can be seen as a large subclass of the conditional approaches. Additionally, we propose an extension to the current set of coregionalization models with some new unexplored proposals. This extension is able to reproduc…
Frequentist and Bayesian approaches for a joint model for prostate cancer risk and longitudinal prostate-specific antigen data
2015
The paper describes the use of frequentist and Bayesian shared-parameter joint models of longitudinal measurements of prostate-specific antigen (PSA) and the risk of prostate cancer (PCa). The motivating dataset corresponds to the screening arm of the Spanish branch of the European Randomized Screening for Prostate Cancer study. The results show that PSA is highly associated with the risk of being diagnosed with PCa and that there is an age-varying effect of PSA on PCa risk. Both the frequentist and Bayesian paradigms produced very close parameter estimates and subsequent 95% confidence and credibility intervals. Dynamic estimations of disease-free probabilities obtained using Bayesian infe…
Enseñanza de Estadística en un contexto multidisciplinar: una experimentación en un instituto italiano
2019
III Congreso Internacional Virtual de Educación Estadística (CIVEEST), 21-24 febrero de 2019. [www.ugr.es/local/fqm126/civeest.html] This paper describes an experiment performed at a Vocational School in Palermo during the school year 2010-11. It was designed to teach Statistics at the Secondary level following a multidisciplinary approach. The didactic activity involved the mathematics, Italian, English language and science teachers. We adapted materials and methods from the M@t.abel E-learning program, which is planned for learning basic mathematics in a middle school, in order to use it for experimentation at a professional school. The assessment of the experimentation is based on teache…
Enseñanza de Estadística en un contexto multidisciplinar: una experimentación en un instituto italiano
2019
III Congreso Internacional Virtual de Educación Estadística (CIVEEST), 21-24 febrero de 2019. [www.ugr.es/local/fqm126/civeest.html]
Inclusión de Tecnologías de la Información y Comunicación en la formación estadística
2011
Tomando en cuenta las dificultades que manifiestan los alumnos para comprender la concepción de modelos estadísticos, en un curso de grado de Probabilidad y Estadística para Ingeniería se planteó la incorporación de recursos didácticos con soporte tecnológico. Para favorecer la interacción se creó un grupo en la plataforma Google donde participaron libremente alumnos y docentes. Paralelamente se diseñó una secuencia didáctica referida a variables aleatorias, con soporte en la planilla Excel. Ambas propuestas fueron evaluadas en forma cualitativa y cuantitativa mediante registros de clases y encuestas a los alumnos. Los resultados permitieron identificar debilidades y fortalezas así como ref…
Propuesta bayesiana para la elaboración de mapas genéticos
2016
En los últimos años, los avances en la investigación biotecnológica, permiten manipular genes o grupos de genes de forma específica en el genoma de los organismos vegetales para producir cultivos con mejores características. Su objetivo es la obtención de especies mejoradas con peculiaridades deseables como un crecimiento más rápido, capaces de una adaptación al medio en el que se desarrollan, más resistentes a plagas o a enfermedades o simplemente proporcionando frutos más grandes, uniformes y de mejor calidad. La investigación y el desarrollo sobre los marcadores moleculares está contribuyendo a la comprensión de los resultados derivados de la herencia de caracteres cuantitativos y a una …