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).
AMMI(yield, genotype, environment, block = NULL, PC = 2,
MSE = NULL, dfr = NULL)Returns a list of class 'AMMIobject' with the following components
The overall least squares genotype means
The overall least squares environment means
The least squares means for the genotype by environment combinations
a two-way table of interaction effects
an ANOVA table for the additive model
an ANOVA table for multiplicative model
Mean Square Error
Degrees of freedom for the MSE
a table of environment scores
a table of genotype scores
AMMI stability value (ASV; Mohammadi and Amri, 2008)
a vector containing yield levels
a vector containing genotype codings
a vector containing environment codings
a vector containing block codes for each environment
the number of PCs that one wants to extract
Mean Squared Error
Residual Degrees of Freedom
Andrea Onofri
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.
WinterWheat <- getAgroData("WinterWheat")
tab <- with(WinterWheat, AMMI(Yield, Genotype, Year, Block, PC = 2))
tab
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