Some Notes on Statistical Analysis of Regional Yield Trials
Date Issued
2004
Date
2004
Author(s)
Chen, Chia-Ying
DOI
zh-TW
Abstract
In this study, we reviewed the statistical analysis of regional yield trials
and proposed some alternatives for conventional statistical analysis.
These alternatives are presented as four notes.
First note is about combined analysis of variance. Regional yield
trials provide information essential to breeders, farmers.
A typical yield trial involves a number of varieties and test sites
within the growing region of a particular crop.
The conventional combined analysis of variance has long been used to analyze
regional yield trial data.
Quite often,
two of the assumptions of this analysis :
(1) error follows normal distribution
(2) individual experiments are required to have homogeneous variance are not met.
For the past decade, computing facilities have been developed for
analyzing mixed-effect models such as SAS Proc Mixed and R lme.
So we will present a short program using Proc Mixed or lme to cope
with the error variance heterogeneity model.
Second note is relevant to the parameter estimation of shifted multiplicative model.
The computation of $hat{psi}$ in SHMM has been a daunting tack
and several algorithm had been proposed to tackle this problem.
We find that this computational difficulty can be handled
reasonably well by the `optimize' function offered by the R language.
The third note is about the additive main effects and
multiplicative interaction (AMMI) model.
We propose an AMMI analysis which can capture most of the
interaction variation by one or two principal components through
reparameterization.
The fourth note is about the impact of variance heterogeneity on AMMI model analysis.
We studied if WLS estimation can provide extra improvement of AMMI
prediction by taking variance heterogeneity into consideration.
To our surprise, both WLS estimates coincide with those from OLS estimation.
So, it shows that variance heterogeneity dose not have any impact on the AMMI model analysis.
Subjects
區域產量試驗
AMMI 分析法
AMMI analysis
regional yield trials
Type
thesis
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