AMMI: AMMI analysis for multienvironment genotype experiments

In statforbiology: Tools for Data Analyses in Biology

AMMI analysis for multienvironment genotype experiments

Description

This function performs the AMMI (Addittive Main effects Multiplicative Interaction) analysis, according to Zobel et al (1988). The function has been described in Onofri and Ciriciofolo (2007).

Usage

AMMI(yield, genotype, environment, block = NULL, PC = 2,
     MSE = NULL, dfr = NULL)

Arguments

yield	a vector containing yield levels
genotype	a vector containing genotype codings
environment	a vector containing environment codings
block	a vector containing block codes for each environment
PC	the number of PCs that one wants to extract
MSE	Mean Squared Error
dfr	Residual Degrees of Freedom

Value

Returns a list of class 'AMMIobject' with the following components

genotype_means	The overall least squares genotype means
environment_means	The overall least squares environment means
interaction_means	The least squares means for the genotype by environment combinations
interaction_effect	a two-way table of interaction effects
additive_ANOVA	an ANOVA table for the additive model
mult_Interaction	an ANOVA table for multiplicative model
MSE	Mean Square Error
dfr	Degrees of freedom for the MSE
environment_scores	a table of environment scores
genotype_scores	a table of genotype scores
stability	AMMI stability value (ASV; Mohammadi and Amri, 2008)

Author(s)

Andrea Onofri

References

Mohammadi, R., Amri, A., 2008. Comparison of parametric and non-parametric methods for selecting stable and adapted durum wheat genotypes in varibale environments. Euphytica 159, 419–432.

Onofri, A., Ciriciofolo, E., 2007. Using R to perform the AMMI analysis on agriculture variety trials. R NEWS 7, 14–19.

Zobel, R. W., Wright, M.J., and Gauch, H. G., 1988. Statistical analysis of a yield trial. Agronomy Journal, 388-393.

Examples

WinterWheat <- getAgroData("WinterWheat")
tab <- with(WinterWheat, AMMI(Yield, Genotype, Year, Block, PC = 2))
tab

statforbiology documentation built on Oct. 30, 2024, 9:13 a.m.