Search results for "Regression analysis"

Ramadan Exposure In Utero and Child Mortality in Burkina Faso: Analysis of a Population-Based Cohort Including 41,025 Children.

2017

Ramadan exposure in utero can be regarded as a natural experiment with which to study how nutritional conditions in utero influence susceptibility to disease later in life. We analyzed data from rural Burkina Faso on 41,025 children born between 1993 and 2012, of whom 25,093 were born to Muslim mothers. Ramadan exposure was assigned on the basis of overlap between Ramadan dates and gestation, creating 7 exclusive categories. We used proportional hazards regression with difference-in-differences analysis to estimate the association between Ramadan exposure at different gestational ages and mortality among children under 5 years of age. Under-5 mortality was 32 deaths per 1,000 child-years. U…

The role of information and communication technologies and logistics organization in the economic performance of Sicilian fruit and vegetable enterpr…

2013

Through a direct survey conducted on a sample of firms operating in the Sicilian fruit and vegetable sector, the present study provides an empirical evidence on the degree of diffusion of ICTs as well as on relationships with the regional distribution system. To pursue this goal, a multiple regression analysis model was implemented to identify which factors affect more the economic results of fruit and vegetable enterprises. The main results of the analysis indicate that firms using specific software for accounting, warehousing, payment and sales orders and contracts, are more likely to obtain higher economic performances under the “coeteris paribus” condition, as well as firms which are eq…

An improvement of June-September rainfall forecasting in the Sahel based upon region April-May moist static energy content (1968-1997)

1999

This study provides statistical evidence that June–September Sahelian rainfall hindcasts currently based on oceanic thermal predictors apprehend more the negative trend than the interannual rainfall variations. Four physically meaningful predictors of June–September Sahel rainfall are first selected through the near-surface April–May information and several experimental hindcasts provided. We then discuss the skills achieved using regression techniques and cross-validated discriminant functions. In that context, 8/11 of the driest seasons and 8/10 of the wettest are correctly predicted. Finally using completely independent training and working periods we show that better and significant hin…

Associations between Finnish 9th grade students' school perceptions, health behaviors, and family factors

2012

PurposeThe aim of this study was to examine the associations between students' perceptions of the psychosocial school environment, health‐compromising behaviours, and selected family factors. The analyses were based on data provided for the Health Behaviour in School‐aged Children Study (2006).Design/methodology/approachThe data were obtained from 1,670 Finnish 9th graders. Logistic regression analysis was performed to identify the associations between school perceptions, health‐compromising behaviours, and selected family factors.FindingsEducational aspiration was found to be the most influential factor connected to health‐compromising behaviour among both genders, favouring students who w…

2020

Introduction/Purpose: Physical activity and sedentary time may associate with physical fitness and body composition. Yet, there exists some observational studies that have investigated the associations of device-based measures of sedentary time and physical activity (PA) with cardiorespiratory fitness (CRF) and body composition but associations with muscular fitness (MF) are less studied.Methods: Objective sedentary time and physical activity was measured by a hip worn accelerometer from 415 young adult men (age: mean 26, standard deviation 7 years). Cardiorespiratory fitness (VO2max) (CRF) was determined using a graded cycle ergometer test until exhaustion. Maximal force of lower extremiti…

Análisis de la relación entre la autoeficacia interpersonal del profesorado y sus niveles de burnout

2017

Introducción. Este trabajo se centra en la evaluación y en el análisis de la capacidad predictiva de la autoeficacia interpersonal del profesorado sobre sus niveles de burnout. Se destaca la utilidad del estudio, dada la ausencia en nuestro contexto de instrumentos de evaluación sobre este constructo psicoeducativo, así como el notable impacto de la percepción de nivel de apoyo social y del mantenimiento de relaciones satisfactorias y de ayuda en el trabajo sobre el estrés docente.Método. En el estudio participan 103 profesores de distintos niveles del sistema educativo es-pañol (55 mujeres, 48 hombres, rango de edad: 24-56), a los que se aplicó una adaptación del Teacher Interpersonal Self…

Analysis of the Overdispersed Clock in the Short-Term Evolution of Hepatitis C Virus: Using the E1/E2 Gene Sequences to Infer Infection Dates in a Si…

2006

Abstract The assumption of a molecular clock for dating events from sequence information is often frustrated by the presence of heterogeneity among evolutionary rates due, among other factors, to positively selected sites. In this work, our goal is to explore methods to estimate infection dates from sequence analysis. One such method, based on site stripping for clock detection, was proposed to unravel the clocklike molecular evolution in sequences showing high variability of evolutionary rates and in the presence of positive selection. Other alternatives imply accommodating heterogeneity in evolutionary rates at various levels, without eliminating any information from the data. Here we pre…

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…