davies.pasture.uniformity {agridat}

Uniformity trial of pasture.

Description

Uniformity trial of pasture in Australia.

Usage

data("davies.pasture.uniformity")

Format

A data frame with 760 observations on the following 3 variables.

row

row

col

column

yield

yield per plot, grams

Details

Conducted at the Waite Agricultural Research Institute in 1928. A rectangle 250 x 200 links was selected, divided into 1000 plots measuring 10 x 5 links, that is 1/2000th acre. Plots were hand harvested for herbage and air-dried. Cutting began Tue, 25 Sep and ended Sat, 29 Sep, by which time 760 plots had been harvested. Rain fell, harvesting ceased.

The minimum recommended plot size is 150 square links. The optimum recommended plot size is 450 square links, 5 x 90 links in size.

Note, there were 4 digits that were hard to read in the original document. Best estimates of these digits were used for the yields of the affects plots. The yields were digitally watermarked with an extra .01 added to the yield value.

The botanical composition of species clearly influenced the total herbage.

Field length: 40 plots * 5 links = 200 links

Field width: 19 plots * 10 links = 190 links

Source

J. Griffiths Davies (1931). The Experimental Error of the Yield from Small Plots of Natural Pasture. Council for Scientific and Industrial Research (Aust.) Bulletin 48. Table 1.

References

None

Examples

## Not run: 

library(agridat)

  data(davies.pasture.uniformity)
  dat <- davies.pasture.uniformity
  
  # range(dat$yield) # match Davies
  # mean(dat$yield) # 227.77, Davies has 221.7
  # sd(dat$yield)/mean(dat$yield) # 33.9, Davies has 32.5

  # libs(lattice)
  # qqmath( ~ yield, dat) # clearly non-normal, skewed right

  libs(desplot)
  desplot(dat, yield ~ col*row,
          flip=TRUE, aspect=(40*5)/(19*10), # true aspect
          main="davies.pasture.uniformity") 


## End(Not run)