Search results for "Regression"
showing 10 items of 2619 documents
Analisi comparativa di modelli euristici e statistici spaziali nella derivazione della suscettibilità da colate rapide di fango e detrito.
2013
La suscettibilità da frana può essere definita come la propensione di una determinata area all’innesco di movimenti di massa, in relazione alle caratteristiche intrinseche dei terreni di copertura e del substrato, delle caratteristiche morfologiche ed alla maggiore esposizione nei confronti degli agenti climatici. Nel corso degli anni sono stati sviluppati vari metodi per valutare la suscettibilità, basati su approcci sia di tipo deterministico che statistico. Tutti i metodi si basano su poche assunzioni fondamentali secondo cui la franosità è controllata da leggi meccaniche che possono essere determinate in modo empirico, statistico o deterministico. Scopo del presente lavoro è quello di v…
Functional principal component analysis of quantile curves
2017
Literature on functional data analysis is mainly focused on estimation of individuals curves and characterization of average dynamics. The idea underlying this proposal is to focus attention on other particular features of the distribution of the observed data, moving from mean functions towards functional quantiles. The motivating examples are functional data sets that are collections of high frequency data recorded along time. As quantiles provide information on various aspects of a time series, we propose a modelling framework for the joint estimation of functional quantiles, varying along time, and functional principal components, summarizing some common dynamics shared by the functiona…
Methodological advances in the functional profiling of genomic studies
2013
In this thesis we present bioinformatic tools and algorithms for the analysis of genomic data such as those generated by microarray devices or next generation sequencing techniques. Particularly, we develop new approaches to gene set analysis. The described procedures should be useful in practice to tackle complex biological experiments, but hopefully will also be methodologically relevant, as they introduce new ways of conceptualizing genomic functional profiling. Our very flexible approach allows for the inclusion of not just one kind of genomic measurement but many. It makes possible, for instance, to analyze expression measurement and genomic variation data at a time. This multidimensio…
Neighborhood Mobility and Unmet Physical Activity Need in Old Age: A 2-Year Follow-Up
2020
Background: Many older people report a willingness to increase outdoor physical activity (PA), but no opportunities for it, a situation termed as unmet PA need. The authors studied whether lower neighborhood mobility and PA precede the development of unmet PA need. Methods: Community-dwelling 75- to 90-year-old people (n = 700) were interviewed annually for 2 years. Unmet PA need, neighborhood mobility, and PA were self-reported. In addition, accelerometer-based step counts were assessed among a subgroup (n = 156). Results: Logistic regression analyses revealed that lower baseline neighborhood mobility (odds ratio 3.02, 95% confidence interval [1.86, 4.90] vs. daily) and PA (odds ratio 4.37…
Study on the financial performance of companies operating in the pharmaceutical industry in romania
2016
Abstract The study aims at determining the financial performance of companies in the pharmaceutical industry between 2009 and 2014 by means of the indicator of the financial return rate, using multiple linear regressions as research method. By analysing the evolution of the share of companies in the pharmaceutical industry based on the trend of the financial rate of return, we can estimate that the number of entities that resort to supporting the financial activities from loans and liabilities is growing in the period under analysis. This is due mainly to the liquidity crisis faced by entities, as a result of the high recovery duration of debts. Also, using the multiple linear regression we…
What is it and how to measure cultural tourism? A longitudinal study with time series for the Spanish case
2013
Por su poder diferenciador, y su débil contingencia a la moda el turismo cultural se ha convertido en un reto para los destinos. No solo dinamiza zonas de interior sino que es una manera para algunos destinos de salvar su patrimonio y crear empleos. Sin embargo, el concepto de turismo cultural es complejo y su delimitación y medición difíciles. En una primera parte teórica, este trabajo realiza una revisión conceptual del turismo cultural enfocando la dialéctica existente entre experiencia y autenticidad, y destacando después la diversidad de tipologías de turismo y de turista cultural. En la parte empírica, después de abordar la dificultad de medición, se presenta un estudio con series tem…
Sparse relative risk survival modelling
2016
Cancer survival is thought to closed linked to the genimic constitution of the tumour. Discovering such signatures will be useful in the diagnosis of the patient and may be used for treatment decisions and perhaps even the development of new treatments. However, genomic data are typically noisy and high-dimensional, often outstripping the number included in the study. Regularized survival models have been proposed to deal with such scenary. These methods typically induce sparsity by means of a coincidental match of the geometry of the convex likelihood and (near) non-convex regularizer.
Assortment, but not knowledge of assortment, affects cooperation and individual success in human groups
2017
The success or failure of human collective action often depends on the cooperation tendencies of individuals in groups, and on the information that individuals have about each other's cooperativeness. However, it is unclear whether these two factors have an interactive effect on cooperation dynamics. Using a decision-making experiment, we confirm that groups comprising individuals with higher cooperation tendencies cooperate at a higher level than groups comprising individuals with low cooperation tendencies. Moreover, assorting individuals with similar cooperation tendency together affected behaviour so that the most cooperative individuals tended to cooperate more and the least cooperativ…
Forward logistic regression for earth-flow landslide susceptibility assessment in the Platani river basin (southern Sicily, Italy)
2013
Forward logistic regression has allowed us to derive an earth-flow susceptibility model for the Tumarrano river basin, which was defined by modeling the statistical relationships between an archive of 760 events and a set of 20 predictors. For each landslide in the inventory, a landslide identification point (LIP) was automatically produced as corresponding to the highest point along the boundary of the landslide polygons, and unstable conditions were assigned to cells at a distance up to 8 m. An equal number of stable cells (out of landslides) was then randomly extracted and appended to the LIPs to prepare the dataset for logistic regression. A model building strategy was applied to enlarg…
Growth curves of sorghum roots via quantile regression with P-splines
2014
Plant roots are a major pool of total carbon in the planet and their dynamics are directly relevant to greenhouse gas balance. Composted wastes are increasingly used in agriculture for environmental and economic reasons and their role as a substitute for traditional fertilizers needs to be tested on all plant components. Here we propose a regression quantile approach based on P-splines to assess, quantify and compare the root growth patterns in two treatment groups respectively undergoing compost and traditional fertilization.