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Browsing Statistics by Author "Cullis, B."
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Item Metadata only Accounting for natural and extraneous variation in the analysis of field experiments(Springer Verlag, 1997) Gilmour, A.; Cullis, B.; Verbyla, A.We identify three major components of spatial variation in plot errors from field experiments and extend the two-dimensional spatial procedures of Cullis and Gleeson (1991) to account for them. The components are nonstationary, large-scale (global) variation across the field, stationary variation within the trial (natural variation or local trend), and extraneous variation that is often induced by experimental procedures and is predominantly aligned with rows and columns. We present a strategy for identifying a model for the plot errors that uses a trellis plot of residuals, a perspective plot of the sample variogram and, where possible, likelihood ratio tests to identify which components are present. We demonstrate the strategy using two illustrative examples. We conclude that although there is no one model that adequately fits all field experiments, the separable autoregressive model is dominant. However, there is often additional identifiable variation present.Item Metadata only Genotype by Environment Variance Heterogeneity in a Two-Stage Analysis(1997) Frensham, A.; Cullis, B.; Verbyla, A.Item Metadata only REML estimation of multiplicative effects in multi-environment variety trials(International Biometrics Society, 1995) Verbyla, A.; Gogel, B.; Cullis, B.Item Metadata only Spatial analysis of multi-environment early generation variety trials(1998) Cullis, B.; Gogel, B.; Verbyla, A.; Thompson, R.