AMMI | R Documentation |

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)
```

`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 |

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) |

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.

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

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