agridat (version 1.23)

forster.wheat.uniformity: Uniformity trial of wheat in Australia.

Description

Uniformity trial of wheat in Australia.

Usage

data("forster.wheat.uniformity")

Format

A data frame with 160 observations on the following 3 variables.

row

row ordinate

col

column ordinate

yield

yield, ounces per plot

Details

This experiment was a repeat of the classic experiment by Mercer and Hall.

Conducted at State Research Farm, Werribee, Victoria, Australia.

Planted 1926. Harvested 1927. An acre of land was selected. Each plot had one double-sown row.

Each plot was 30 x 20 links. The whole experiment was 300 x 320 links.

Near the west edge, a strip was damaged by cart tracks and excluded.

The field was marked into quarters and one quarter was subdivided and harvested at a time.

Each quarter was cut into 5 strips of 8 plots.

Field length: 16 plots * 20 links = 320 links (211 feet).

Field width: 10 plots * 30 links = 300 links (197 feet).

Note: It is not clear how a strip "a few yards wide" could be omitted and yet the dimensions of the whole area still be 300 x 320 links.

Since the omitted strip is about 1/3 the width of a plot, we (agridat authors) decided to ignore the omitted strip.

This electronic data was manually typed from the source on 2023-04-12. Summary statistics of this electronic data differ slightly from the summaries in Forster, indicating possible typos or rounding of the printed yield values in the paper. Values were checked by hand and match the paper.

References

None

Examples

if (FALSE) {
  require(agridat)
  data(forster.wheat.uniformity)
  dat <- forster.wheat.uniformity
  
  mean(dat$yield)
  # 135.97 # Forster says 136.5
  sd(dat$yield)
  # 10.68  # Forster says 10.9
  
  # Compare to Forster table 3.  Slight differences.
  table( cut(dat$yield,
             breaks = c(106,111,116,121,126,131,136,141,
                        146,151,156,161,166)+.5) )
  # Forster has 5 plots in the 157-161 bin, but we show 6.
  # I filtered the data for this bin and verified our data
  # matches the layout in the paper.
  filter(dat, yield>156.5, yield<161.5)

  libs(desplot)
  desplot(dat, yield ~ col*row,
          flip=TRUE, aspect=(16*20)/(10*30), # true aspect
          main="forster.wheat.uniformity")
}