AMMI is a menu for fitting, to data classified by two factors, a model which
involves the Additive Main effects of ANOVA along with the Multiplicative
Interaction effects of principal components analysis (PCA). The method is used
when analysing data from a series of trials with crop genotypes. A principal
components model is fitted to the residuals from the ANOVA and the resulting
scores, called the I (for interaction) PCA scores, are calculated for both the
genotypes and the trials or environments. The menu can handle replicate
observations that make up the genotype x environment means by specifying the
replicate observations, and a replicate factor using the Replication box. When
constructing the analysis-of-variance table, AMMI assumes that the replicates
arise from the use of a randomized block design within each environment. No
missing values are allowed, and there must be equal replication.
Available Data
This lists data structures appropriate to the current input field. It lists
either factors for use in specifying the genotypes, environments and
replication, or variates for specifying the data. The contents will change as
you move from one field to the next. Double-click on a name to copy it to the
current input field; alternatively, you can type the name directly into the
input field.
Data
Provides a space for you to specify a variate containing the data.
Genotype
A factor to specify the genotypes.
Environments
A factor to specify the environments.
Replication
Provides a space for you to specify a factor for the replication; this should
be left blank if the data comprises of just the genotype by environment means.
See Also