Generalized bootstrap method for assessment of uncertainty in semivariogram inference

Mathematical Geosciences
By:  and 

Links

Abstract

The semivariogram and its related function, the covariance, play a central role in classical geostatistics for modeling the average continuity of spatially correlated attributes. Whereas all methods are formulated in terms of the true semivariogram, in practice what can be used are estimated semivariograms and models based on samples. A generalized form of the bootstrap method to properly model spatially correlated data is used to advance knowledge about the reliability of empirical semivariograms and semivariogram models based on a single sample. Among several methods available to generate spatially correlated resamples, we selected a method based on the LU decomposition and used several examples to illustrate the approach. The first one is a synthetic, isotropic, exhaustive sample following a normal distribution, the second example is also a synthetic but following a non-Gaussian random field, and a third empirical sample consists of actual raingauge measurements. Results show wider confidence intervals than those found previously by others with inadequate application of the bootstrap. Also, even for the Gaussian example, distributions for estimated semivariogram values and model parameters are positively skewed. In this sense, bootstrap percentile confidence intervals, which are not centered around the empirical semivariogram and do not require distributional assumptions for its construction, provide an achieved coverage similar to the nominal coverage. The latter cannot be achieved by symmetrical confidence intervals based on the standard error, regardless if the standard error is estimated from a parametric equation or from bootstrap.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Generalized bootstrap method for assessment of uncertainty in semivariogram inference
Series title Mathematical Geosciences
DOI 10.1007/s11004-010-9269-6
Volume 43
Issue 2
Year Published 2011
Language English
Publisher Springer
Contributing office(s) Eastern Energy Resources Science Center
Description 26 p.
First page 203
Last page 228