ASTAB.AMMI {ammistability} | R Documentation |

`ASTAB.AMMI`

computes the AMMI Based Stability Parameter (ASTAB)
(Rao and Prabhakaran 2005) considering all significant
interaction principal components (IPCs) in the AMMI model. Using ASTAB, the
Simultaneous Selection Index for Yield and Stability (SSI) is also calculated
according to the argument `ssi.method`

.

ASTAB.AMMI(model, n, alpha = 0.05, ssi.method = c("farshadfar", "rao"), a = 1)

`model` |
The AMMI model (An object of class |

`n` |
The number of principal components to be considered for computation. The default value is the number of significant IPCs. |

`alpha` |
Type I error probability (Significance level) to be considered to identify the number of significant IPCs. |

`ssi.method` |
The method for the computation of simultaneous selection
index. Either |

`a` |
The ratio of the weights given to the stability components for
computation of SSI when |

The AMMI Based Stability Parameter value (\(ASTAB\)) (Rao and Prabhakaran 2005) is computed as follows:

\[ASTAB = \sum_{n=1}^{N'}\lambda_{n}\gamma_{in}^{2}\]Where, \(N'\) is the number of significant IPCs (number of IPC that were retained in the AMMI model via F tests); \(\lambda_{n}\) is the singular value for \(n\)th IPC and correspondingly \(\lambda_{n}^{2}\) is its eigen value; and \(\gamma_{in}\) is the eigenvector value for \(i\)th genotype.

A data frame with the following columns:

`ASTAB` |
The ASTAB values. |

`SSI` |
The computed values of simultaneous selection index for yield and stability. |

`rASTAB` |
The ranks of ASTAB values. |

`rY` |
The ranks of the mean yield of genotypes. |

`means` |
The mean yield of the genotypes. |

The names of the genotypes are indicated as the row names of the data frame.

Rao AR, Prabhakaran VT (2005).
“Use of AMMI in simultaneous selection of genotypes for yield and stability.”
*Journal of the Indian Society of Agricultural Statistics*, **59**, 76–82.

library(agricolae) data(plrv) # AMMI model model <- with(plrv, AMMI(Locality, Genotype, Rep, Yield, console = FALSE)) # ANOVA model$ANOVA # IPC F test model$analysis # Mean yield and IPC scores model$biplot # G*E matrix (deviations from mean) array(model$genXenv, dim(model$genXenv), dimnames(model$genXenv)) # With default n (N') and default ssi.method (farshadfar) ASTAB.AMMI(model) # With n = 4 and default ssi.method (farshadfar) ASTAB.AMMI(model, n = 4) # With default n (N') and ssi.method = "rao" ASTAB.AMMI(model, ssi.method = "rao") # Changing the ratio of weights for Rao's SSI ASTAB.AMMI(model, ssi.method = "rao", a = 0.43)

[Package *ammistability* version 0.1.2 Index]