agridat (version 1.16)

iyer.wheat.uniformity: Uniformity trials of wheat in India

Description

Uniformity trials of wheat in India.

Usage

data("iyer.wheat.uniformity")

Format

A data frame with 2000 observations on the following 3 variables.

row

row

col

column

yield

yield, ounces per plot

Details

Data collected at the Agricultural Sub-station in Karnal, India, in April 1978. A net area of 400 ft x 125 ft was harvested by dividing it into 80x25 units 5 ft x 5 ft after eliminating a minimum border of 3.5 ft all around the net area.

Field width: 80 plots * 5 feet = 400 feet

Field length: 25 rows * 5 feet = 125 feet

In a second paper, Iyer used this data to compare random vs. balanced arrangements of treatments to plots, with the conclusion that "it is very difficult to say which [method] is better. However, there is some tendency for the randomized arrangements to give more accurate results."

References

None.

Examples

# NOT RUN {
  
  data(iyer.wheat.uniformity)
  dat <- iyer.wheat.uniformity

  require(desplot)
  desplot(yield ~ col*row, data=dat,
          main="iyer.wheat.uniformity", tick=TRUE, 
          aspect=(25*5)/(80*5)) # true aspect

  # not exactly the same as Iyer table 1, p. 241
  var(subset(dat, col <= 20)$yield)
  var(subset(dat, col > 20 & col <= 40)$yield)
  var(subset(dat, col > 40 & col <= 60)$yield)
  var(subset(dat, col > 60)$yield)
  
  # cv for 1x1 whole-field
  # sd(dat$yield)/mean(dat$yield)
  # 18.3

# }