Results 251 to 260 of about 2,210,403 (291)

A Note on Variances in the Components of Variance Model

The American Statistician, 1971
In a components of variance model the variance of individual observations and of various averages of observations are shown to be dependent upon the design-that is, upon the sampling scheme. For example, using the usual notation, for the nested random model yij = iA+ ri + eJ(i), i = 1, 2, . . . I, and j = 1 2, ... J, Var(ysi) = [(I 1)J/(IJ 1)]a2 + a2e.
openaire   +1 more source

Components of variance

1981
So far, the examples of analysis-of-variance problems that we have considered all fall within the scope of what we call the ‘fixed effects’ analysis, or the ‘model I’ situation. In these problems the questions being asked are questions about contrasts of sets of means.
openaire   +1 more source

Variance components of gingival thickness

Journal of Periodontal Research, 2005
Objectives:  Distinct periodontal phenotypes have been identified by cluster analysis, which is an explorative method with very low external validity. The aim of the present study was to investigate variance components of facial gingival thickness in young adults with mild gingivitis.Material and methods:  Thirty‐three non‐smoking females, 18–23 years ...
H P, Müller, E, Könönen
openaire   +2 more sources

Exact Tests for Variance Components

Biometrics, 1996
Summary: \textit{J. Öfversten} [ibid. 49, No. 1, 45-57 (1993; Zbl 0771.62053)] presented two kinds of exact \(F\)-tests for variance components in unbalanced mixed linear models. Specifically, methods were developed for models with one random factor, nested classifications, and models with interaction between random factors.
openaire   +1 more source

Nonlinear Regression With Variance Components

Journal of the American Statistical Association, 1992
Abstract The nonlinear model with variance components, which combines a nonlinear model for the mean with additive random effects, is applicable to split-plot and nested experiments. We propose two methods of estimation for the parameters of the nonlinear model for the mean: (1) estimated generalized least squares (EGLS), and (2) maximum likelihood ...
Marcia L. Gumpertz, Sastry G. Pantula
openaire   +1 more source

Variance Components and Disconnected Data

Biometrics, 1978
Summary It has been suggested that disconnected data pose problems in variance component estimation and that the dlscarding of certain sections of a data set is a possible solution. In contrast, it is shown in this paper that estimators of variance components can be derived from disconnected data by applying Henderson's Method III without modification.
openaire   +2 more sources

Variance Components

Journal of Marketing Research, 1993
Peter H. Westfall, S. R. Searle, G. Casella, C. E. McCulloch   +3 more
  +4 more sources

Components of Variance in Polydrug Use

International Journal of the Addictions, 1981
Forty-seven people who first attended any London drug clinic in 1971 were asked at what age they first used various drugs and how frequently each was used during every subsequent year. For age of first use, substantial significant variance components due both to drugs and subjects and to the interaction between them confirmed that certain substances ...
openaire   +2 more sources

Statistical Analysis of Negative Variance Components in the Estimation of Variance Components

2008
This paper analyzes the problem of negative variance components in the estimation of variance components from the statistical point of view, based on two kinds of estimators of variance components. Our analysis shows that too low relative accuracy and too large errors of the estimated variance components in comparison with the variance component itself
B. Gao, S. Li, W. Li, S. Li, X. Wang
openaire   +1 more source

Transformations for components of variance and covariance

Biometrika, 1985
Variance component models make various independence assumptions and typically assume effects are normally distributed. Here we assume that the data, possibly after suitable transformation, satisfy such a model. An analysis of transformations for balanced variance component models is presented, components of covariance being incorporated in the ...
openaire   +2 more sources