DZ.AMMI {ammistability} | R Documentation |

`DZ.AMMI`

computes the Zhang's D Parameter values or AMMI statistic
coefficient or AMMI distance or AMMI stability index
(\(\textrm{D}_{\textrm{z}}\))
(Zhang et al. 1998) considering all significant
interaction principal components (IPCs) in the AMMI model. It is the distance
of IPC point from origin in space. Using
\(\textrm{D}_{\textrm{z}}\), the Simultaneous Selection Index for Yield
and Stability (SSI) is also calculated according to the argument
`ssi.method`

.

DZ.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 Zhang's D Parameter value (\(D_{z}\)) (Zhang et al. 1998) is computed as follows:

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

A data frame with the following columns:

`DZ` |
The DZ values. |

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

`rDZ` |
The ranks of DZ 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.

Zhang Z, Lu C, Xiang Z (1998).
“Analysis of variety stability based on AMMI model.”
*Acta Agronomica Sinica*, **24**(3), 304–309.
http://zwxb.chinacrops.org/EN/Y1998/V24/I03/304.

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) DZ.AMMI(model) # With n = 4 and default ssi.method (farshadfar) DZ.AMMI(model, n = 4) # With default n (N') and ssi.method = "rao" DZ.AMMI(model, ssi.method = "rao") # Changing the ratio of weights for Rao's SSI DZ.AMMI(model, ssi.method = "rao", a = 0.43)

[Package *ammistability* version 0.1.2 Index]