agridat (version 1.23)

piepho.barley.uniformity: Uniformity trial of barley

Description

Uniformity trial of barley in Germany

Usage

data("piepho.barley.uniformity")

Format

A data frame with 1080 observations on the following 5 variables.

row

row ordinate

col

column ordinate

yield

yield per plot

Details

Uniformity trial of barley at Ihinger Hof farm, conducted by the University of Hohenheim, Germany, in 2007.

Note: The paper by Piepho says "The trial had 30 rows and 36 columns. Plot widths were 1.90 m along rows and 3.73 m along columns." This is confirmed by the variograms in Figure 1. It is not clear what "along rows" and "along columns" means in English.

However, the SAS code supplement to the paper, called "PBR_1654_sm_example1.sas", has row=1-36, col=1-30.

References

None

Examples

if (FALSE) {
  data(piepho.barley.uniformity) 
  dat <- piepho.barley.uniformity
  libs(desplot)
  desplot(dat, yield ~ col*row,
          tick=TRUE, aspect=(36*3.73)/(30*1.90),
          main="piepho.barley.uniformity.csv")

  if(require("asreml", quietly=TRUE)){
    libs(asreml,dplyr,lucid)
    dat <- mutate(dat, x=factor(col), y=factor(row))
    dat <- arrange(dat, x, y)
  
    # Piepho AR1xAR1 model (in random term, NOT residual)
    m1 <- asreml(data=dat,
                 yield ~ 1, 
                 random = ~ x + y + ar1(x):ar1(y), 
                 residual = ~  units,
                 na.action=na.method(x="keep") )
    m1 <- update(m1)
    # Match Piepho table 3, footnote 4: .9671, .9705 for col,row correlation
    # Note these parameters are basically at the boundary of the parameter
    # space. Questionable fit.
    lucid::vc(m1)
  }
}