Search results for "Regression analysi"
showing 10 items of 813 documents
Selection of the Best Subset of Variables in Regression and Time Series Models
2009
The problem of variable selection is one of the most pervasive model selection problems in statistical applications. Often referred to as the problem of subset selection, it arises when one wants to model the relationship between a variable of interest and a subset of potential explanatory variables or predictors, but there is uncertainty about which subset to use. Several papers have dealt with various aspects of the problem but it appears that the typical regression user has not benefited appreciably. One reason for the lack of resolution of the problem is the fact that it is has not been well defined. Indeed, it is apparent that there is not a single problem, but rather several problems …
Relationships among customer orientation, service orientation and job satisfaction in financial services
2005
PurposeThe present study attempts to contribute to the knowledge of how customer orientation (CO), service orientation (SO) and job satisfaction (JS) are defined and relate to each other. It explores the relationships between CO and JS by analysing a company providing intermediation services to the banking sector, in its external finance division.Design/methodology/approachAfter the literature review, the method of empirical analysis consisting in quantitative intervention with an ad hoc survey using a structured questionnaire was developed. Regression analysis with mediation is used to contrast the hypotheses on the links between the constructs analysed.FindingsBoth reliability and factori…
Regression with Imputed Covariates: A Generalized Missing Indicator Approach
2011
A common problem in applied regression analysis is that covariate values may be missing for some observations but imputed values may be available. This situation generates a trade-off between bias and precision: the complete cases are often disarmingly few, but replacing the missing observations with the imputed values to gain precision may lead to bias. In this paper we formalize this trade-off by showing that one can augment the regression model with a set of auxiliary variables so as to obtain, under weak assumptions about the imputations, the same unbiased estimator of the parameters of interest as complete-case analysis. Given this augmented model, the bias-precision trade-off may then…
Application of molecular topology to the prediction of antiparasitic activity against Giardia intestinalis and Trichomonas vaginalis of 2-Acylamino-n…
2020
Giardia intestinalis y Trichomonas vaginalis destacan por su importancia clínica. G. intestinalis causa la giardiosis, una parasitosis de gran importancia epidemiológica y clínica por presentar una elevada prevalencia. T. vaginalis causa la tricomoniasis, la enfermedad de transmisión sexual (ETS) no viral con mayor incidencia del mundo. Ambas parasitosis comparten el mismo tratamiento farmacológico: los nitroimidazoles. Se ha aplicado la topología molecular en la búsqueda de derivados del 2-Acylamino-nitro-1,3-tiazol con actividad antiparasitaria frente a G. intestinalis y T. vaginalis . Con el análisis lineal discriminante se obtuvo un modelo capaz de clasificar correctamente el 92,85 % de…
Shareholder Wealth Effects of Women on Boards Promoting Policies: Evidence from Germany
2017
This study discusses differences in the effectiveness of voluntary and mandatory policies promoting women on boards and their potential effects on stock price returns. Furthermore, it classifies the announcements of the policy proposals discussed in Germany and analyzes their impact using event study methodology. The event date identification follows a two-step procedure employing search engine query data from GoogleTrends and traditional search methods using Lexis-Nexis and newspapers. One key event produces negative significant cumulative abnormal stock returns (CAR) of approximately 1.3 percentage points. Further regression analysis of the CAR reveals that the share of women on the super…
Causal Inference in Geoscience and Remote Sensing From Observational Data
2020
Establishing causal relations between random variables from observational data is perhaps the most important challenge in today’s science. In remote sensing and geosciences, this is of special relevance to better understand the earth’s system and the complex interactions between the governing processes. In this paper, we focus on an observational causal inference, and thus, we try to estimate the correct direction of causation using a finite set of empirical data. In addition, we focus on the more complex bivariate scenario that requires strong assumptions and no conditional independence tests can be used. In particular, we explore the framework of (nondeterministic) additive noise models, …
Spatial noise-aware temperature retrieval from infrared sounder data
2020
In this paper we present a combined strategy for the retrieval of atmospheric profiles from infrared sounders. The approach considers the spatial information and a noise-dependent dimensionality reduction approach. The extracted features are fed into a canonical linear regression. We compare Principal Component Analysis (PCA) and Minimum Noise Fraction (MNF) for dimensionality reduction, and study the compactness and information content of the extracted features. Assessment of the results is done on a big dataset covering many spatial and temporal situations. PCA is widely used for these purposes but our analysis shows that one can gain significant improvements of the error rates when using…
Incidence of DAA failure and the clinical impact of retreatment in real-life patients treated in the advanced stage of liver disease: Interim evaluat…
2017
Background: Few data are available on the virological and clinical outcomes of advanced liver disease patients retreated after first-line DAA failure. Aim: To evaluate DAA failure incidence and the retreatment clinical impact in patients treated in the advanced liver disease stage. Methods: Data on HCV genotype, liver disease severity, and first and second line DAA regimens were prospectively collected in consecutive patients who reached the 12-week post-treatment and retreatment evaluations from January 2015 to December 2016 in 23 of the PITER network centers. Results: Among 3,830 patients with advanced fibrosis (F3) or cirrhosis, 139 (3.6%) failed to achieve SVR. Genotype 3, bilirubin lev…
Numerical Calibration of a Simplified Model for FRP Confinement of Columns
2018
This paper presents the calibration of a simplified analytical model for concrete columns confined by fiber reinforced polymer (FRP) jackets. The model allows evaluating the increase of strength, ductility and dissipated energy without defining the lateral confinement pressure and it can be easily extended for the assessment of FRP confinement in design applications. This model was obtained by a simplified procedure based on the best fit of experimental data available in the literature and the coefficient of determination (R2) was evaluated in order to estimate the accuracy of the regression analysis. A numerical database resulting from finite element (FE) analyses was compiled and reported…
Epidemiology of intensive care unit-acquired sepsis in Italy: Results of the SPIN-UTI network
2018
Background. Sepsis is the major cause of mortality from any infectious disease worldwide. Sepsis may be the result of a healthcare associated infection (HAI): the most frequent adverse events during care delivery especially in Intensive Care Units (ICUs). The main aim of the present study was to describe the epidemiology of ICU-acquired sepsis and related outcomes among patients enrolled in the framework of the Italian Nosocomial Infections Surveillance in ICUs - SPIN-UTI project. Study design. Prospective multicenter study. Methods. The SPIN-UTI network adopted the European protocols for patient-based HAI surveillance. Results. During the five editions of the SPIN-UTI project, from 2008 to…