Description Usage Arguments Details Value References See Also Examples

`FA.AMMI`

computes the Stability Measure Based on Fitted AMMI Model (FA)
(Raju, 2002) considering all significant interaction principal components
(IPCs) in the AMMI model. Using FA, the Simultaneous Selection Index for
Yield and Stability (SSI) is also calculated according to the argument
`ssi.method`

.

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 Stability Measure Based on Fitted AMMI Model
(*FA*) is computed as follows:

*FA =
∑ ^{N'}_{n=1} λ^{2}_{n}γ^{2}_{in}*

Where, *N'* is the number of significant
IPCs (number of IPC that were retained in the AMMI model via F tests);
*λ _{n}* is the
singular value for

When *N'* is replaced by 1 (only first
IPC axis is considered for computation), then the parameter
*FP* can be estimated (Zali et al.,
2012).

*FP
=λ ^{2}_{1}γ^{2}_{i1}*

When *N'* is replaced by 2 (only first
two IPC axes are considered for computation), then the parameter
*B* can be estimated (Zali et al., 2012).

*B =
∑ ^{2}_{n=1} λ^{2}_{n}γ^{2}_{in}*

When *N'* is replaced by
*N* (All the IPC axes are considered for
computation), then the parameter estimated is equivalent to Wricke's
ecovalence (*W _{(AMMI)}*)
(Wricke, 1962; Zali et al., 2012).

*W _{(AMMI)} =
∑^{N}_{n=1} λ^{2}_{n}γ^{2}_{in}*

A data frame with the following columns:

`FA` |
The FA values. |

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

`rFA` |
The ranks of FA 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.

wricke_method_1962ammistability

\insertRefraju_study_2002ammistability

\insertRefzali_evaluation_2012ammistability

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | ```
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)
FA.AMMI(model)
# With n = 4 and default ssi.method (farshadfar)
FA.AMMI(model, n = 4)
# With default n (N') and ssi.method = "rao"
FA.AMMI(model, ssi.method = "rao")
# Changing the ratio of weights for Rao's SSI
FA.AMMI(model, ssi.method = "rao", a = 0.43)
``` |

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