Search results for "One-way analysis of variance"
showing 7 items of 7 documents
On the Estimation of the Volatility-Growth Link
2012
It is common practice to estimate the volatility-growth link by specifying a standard growth equation such that the variance of the error term appears as an explanatory variable in this growth equation. The variance in turn is modeled by a second equation. Hardly any of existing applications of this framework includes exogenous controls in this second variance equation. Our theoretical findings suggest that the absence of relevant explanatory variables in the variance equation leads to a biased and inconsistent estimate of the volatility-growth link. Our simulations show that this effect is large. Once the appropriate controls are included in the variance equation consistency is restored. I…
STUDENTS’ READINESS FOR MASSIVE OPEN ONLINE COURSES (MOOCS) IN LATVIA
2020
MOOCs have gained popularity increasingly more and more with their open online approach and mass engagement. They could play an important role in higher education. But the question remains whether students are ready for it. The aim of the study was to find out what students' understanding of online learning was and to what extent they were prepared for MOOCs. A research question was raised: there is a relationship among technical competencies, socio-communication competencies, self-efficacy, self-directedness and MOOCs readiness. The survey-monkey's electronic platform was used for data extraction. Open-ended questions were asked on the 4-point Likert scale. According to the research questi…
Do GOLD stages of COPD severity really correspond to differences in health status?
2003
The purpose of this study was to assess whether different stages of chronic obstructive pulmonary disease (COPD) severity defined according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria correlate with meaningful differences in health status. A total of 381 COPD patients, aged 73+/-6 yrs, were classified in the five GOLD stages. Disease-specific (St George Respiratory Questionnaire (SGRQ)) and generic indexes of health status were measured in all patients. Multivariate analysis of covariance or Kruskal Wallis tests were used to compare health status indexes across the spectrum of GOLD stages of COPD severity. GOLD stages of COPD severity significantly differed…
Association between nasal and bronchial resistance in patients with COPD
2018
Background: During the past decade, various studies have documented the presence of sinonasal inflammation in lower airways diseases. The influence of airways inflammation on nasal airways patency was demonstrated in asthmatic patients; however, such association was not confirmed in patients with COPD. Purpose: The aim of the study was to compare the relationship between nasal resistance and lower airways patency in COPD patients and healthy controls. Material and Methods: 4-Phase-Rhinomanometry and spirometry were performed on COPD patients (n=26) and in the corresponding age control group (n=15). To compare the effective nasal resistance in inspiration, expiration and total breathing (Ref…
Use of functionals in linearization and composite estimation with application to two-sample survey data
2009
An important problem associated with two-sample surveys is the estimation of nonlinear functions of finite population totals such as ratios, correlation coefficients or measures of income inequality. Computation and estimation of the variance of such complex statistics are made more difficult by the existence of overlapping units. In one-sample surveys, the linearization method based on the influence function approach is a powerful tool for variance estimation. We introduce a two-sample linearization technique that can be viewed as a generalization of the one-sample influence function approach. Our technique is based on expressing the parameters of interest as multivariate functionals of fi…
Change-points detection for variance piecewise constant models
2011
A new approach based on the fit of a generalized linear regression model is introduced for detecting change-points in the variance of heteroscedastic Gaussian variables, with piecewise constant variance function. This approach overcome some limitations of both exact and approximate well-known methods that are based on successive application of search and tend to overestimate the real number of changes in the variance of the series. The proposed method just requires the computation of a gamma GLM with log-link, resulting in a very efficient algorithm even with large sample size and many change points to be estimated.
Fruit Quality Traits of Two Apricot Cultivars
2010
In this trial we evaluated physical and chemical fruit quality traits and sensory profile of two late-ripening apricot cultivars ‘Vitillo’ and ‘Pellecchiella’. Fruits were harvested at full maturation in three different pickings, at 4 day intervals, to ensure the same fruit quality. To verify quality among different pickings, weight, diameter, soluble solid content, titratable acidity, pH, colour were recorded. To describe and quantify the sensory characteristics of apricot fruits a panel of 10 judges generated 16 descriptors. For each of these attributes judges assigned a score from 1 to 9. Qualitative and sensory data for each attribute were submitted to one way Analysis of Variance (ANOV…