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Resampling Methodology in Spatial Prediction and Repeated Measures Time SeriesRister, Krista Dianne 2010 December 1900 (has links)
In recent years, the application of resampling methods to dependent data, such
as time series or spatial data, has been a growing field in the study of statistics. In
this dissertation, we discuss two such applications.
In spatial statistics, the reliability of Kriging prediction methods relies on the
observations coming from an underlying Gaussian process. When the observed data
set is not from a multivariate Gaussian distribution, but rather is a transformation
of Gaussian data, Kriging methods can produce biased predictions. Bootstrap
resampling methods present a potential bias correction. We propose a parametric
bootstrap methodology for the calculation of either a multiplicative or additive bias
correction factor when dealing with Trans-Gaussian data. Furthermore, we investigate
the asymptotic properties of the new bootstrap based predictors. Finally, we
present the results for both simulated and real world data.
In time series analysis, the estimation of covariance parameters is often of utmost
importance. Furthermore, the understanding of the distributional behavior of
parameter estimates, particularly the variance, is useful but often difficult. Block
bootstrap methods have been particularly useful in such analyses. We introduce a new procedure for the estimation of covariance parameters for replicated time series
data.
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Contributions to Estimation and Testing Block Covariance Structures in Multivariate Normal ModelsLiang, Yuli January 2015 (has links)
This thesis concerns inference problems in balanced random effects models with a so-called block circular Toeplitz covariance structure. This class of covariance structures describes the dependency of some specific multivariate two-level data when both compound symmetry and circular symmetry appear simultaneously. We derive two covariance structures under two different invariance restrictions. The obtained covariance structures reflect both circularity and exchangeability present in the data. In particular, estimation in the balanced random effects with block circular covariance matrices is considered. The spectral properties of such patterned covariance matrices are provided. Maximum likelihood estimation is performed through the spectral decomposition of the patterned covariance matrices. Existence of the explicit maximum likelihood estimators is discussed and sufficient conditions for obtaining explicit and unique estimators for the variance-covariance components are derived. Different restricted models are discussed and the corresponding maximum likelihood estimators are presented. This thesis also deals with hypothesis testing of block covariance structures, especially block circular Toeplitz covariance matrices. We consider both so-called external tests and internal tests. In the external tests, various hypotheses about testing block covariance structures, as well as mean structures, are considered, and the internal tests are concerned with testing specific covariance parameters given the block circular Toeplitz structure. Likelihood ratio tests are constructed, and the null distributions of the corresponding test statistics are derived.
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