agridat (version 1.23)

huehn.wheat: Multi-environment trial of wheat to illustrate stability statistics

Description

Multi-environment trial to illustrate stability statistics

Usage

data("huehn.wheat")

Format

A data frame with 200 observations on the following 3 variables.

gen

genotype

env

environment

yield

yield dt/ha

Details

Yields for a winter-wheat trial of 20 genotypes at 10 environments.

Note: Huehn 1979 does not use genotype-centered data when calculating stability statistics.

References

Nassar, R and Huehn, M. (1987). Studies on estimation of phenotypic stability: Tests of significance for nonparametric measures of phenotypic stability. Biometrics, 43, 45-53.

Examples

if (FALSE) {

  library(agridat)
  data(huehn.wheat)
  dat <- huehn.wheat
  
  # Nassar & Huehn, p. 51 "there is no evidence for differences in stability
  # among the 20 varieties".
  libs(gge)
  m1 <- gge(dat, yield ~ gen*env)
  biplot(m1, main="huehn.wheat")
  
  libs(reshape2)
  datm <- acast(dat, gen~env, value.var='yield')

  apply(datm,1,mean) # Gen means match Huehn 1979 table 1
  apply(datm,2,mean) # Env means
  apply(datm, 2, rank) # Ranks match Huehn table 1

  # Huehn 1979 did not use genotype-centered data, and his definition
  # of S2 is different from later papers.

  # I'm not sure where 'huehn' function is found
  # apply(huehn(datm, corrected=FALSE), 2, round,2) # S1 matches Huehn
  ##          MeanRank   S1
  ## Jubilar      6.70 3.62
  ## Diplomat     8.35 5.61
  ## Caribo      11.20 6.07
  ## Cbc710      13.65 6.70

  # Very close match to Nassar & Huehn 1987 table 4.
  # apply(huehn(datm, corrected=TRUE), 2, round,2)
  ##          MeanRank   S1   Z1    S2   Z2
  ## Jubilar      10.2 4.00 5.51 11.29 4.29
  ## Diplomat     11.0 6.31 0.09 27.78 0.27
  ## Caribo       10.6 6.98 0.08 34.49 0.01
  ## Cbc710       10.9 8.16 1.78 47.21 1.73

}