stability.shu: Stability variance

In agrostab: Stability Analysis for Agricultural Research

Description

This function calculates the Shukla's stability variance.

Usage

stability.shu(dataf, res_var, gen_var, env_var, rep_var, plotIt = TRUE)

Arguments

dataf	the name of the data frame containing the data to analyze.
res_var	the response variable.
gen_var	the genotypes variable.
env_var	the environments variable.
rep_var	the replications variable.
plotIt	a logical value specifying if plot should be drawn; default is TRUE

Value

Returns a list of two objects:

ANOVA

the analysis of variance table

scores

the data frame object of stability analysis results:

• bi regression of genotype means on environmental means

• t_value t-values for gypothesis that bi=0

• p_value p-values for gypothesis that bi=0

• sigma Shukla's stability variance value

• pf_value p-values for gypothesis that sigmai=0

References

Shukla, G.K. 1972. Some statistical aspects of partitioning genotype-environmental components of variability. Heredity 29: 237-245. doi: 10.1038/hdy.1972.87

Examples

data(exp_data)
stability.shu(exp_data,"yield","gen","env","rep")

Example output

$ANOVA
                Df  Sum Sq Mean Sq F value    Pr(>F)    
Genotypes        6  4.5017  0.7503  7.3527 6.727e-05 ***
Environments     5 29.7674  5.9535 64.8946              
Gen x Env       30  3.0612  0.1020  1.1123              
  Heterogeneity  6  0.7112  0.1185  1.2106  0.335034    
  Balance       24  2.3500  0.0979  1.0673              
  Novosib2                  0.0917 21.0182 1.443e-13 ***
  Novosib3                  0.0300  6.8630 2.054e-05 ***
  Novosib32                 0.0645 14.7706 2.217e-10 ***
  Novosib40                 0.0075  1.7258  0.137566    
  Novosib51                 0.0003  0.0793  0.995265    
  Obskaya_o                 0.0163  3.7389  0.004183 ** 
  Omskaya6                  0.0277  6.3529 4.752e-05 ***
Pooled error    84  0.3666  0.0044                      
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

$scores
                   bi   t_value    p_value       sigma     pf_value
Novosib2   0.10438414 0.4284848 0.69036385 0.275221877 1.443290e-13
Novosib3   0.02333879 0.1538333 0.88519031 0.089867136 2.053824e-05
Novosib32 -0.34950589 2.9170499 0.04337118 0.193412914 2.216733e-10
Novosib40  0.13615963 2.0539155 0.10920381 0.022597802 1.375656e-01
Novosib51 -0.05334029 0.8662612 0.43521588 0.001037802 9.952645e-01
Obskaya_o  0.03335219 0.2790395 0.79404724 0.048958469 4.182574e-03
Omskaya6   0.10561143 0.7669413 0.48587883 0.083187210 4.751790e-05

Warning message:
In anova.lm(model2) :
  ANOVA F-tests on an essentially perfect fit are unreliable

agrostab documentation built on Oct. 30, 2019, 10:51 a.m.