agridat (version 1.16)

ryder.groundnut: Wet and dry groundnut yields

Description

Wet and dry groundnut yields with a possible data error.

Format

A data frame with 24 observations on the following 6 variables.

block

block

row

row

col

column

gen

genotype factor

wet

wet yield, kg/plot

dry

dry yield, kg/plot

Details

Ryder (1981) uses this data to discuss the importance of looking at the field plan for an experiment. Based on analysis of the residuals, he suggests that varieties A and B in block 3 may have had their data swapped.

Examples

# NOT RUN {
data(ryder.groundnut)
dat <- ryder.groundnut

# RCB model
m1 <- lm(dry~block+gen,dat)
dat$res1 <- resid(m1)

# Table 3 of Ryder.  Scale up from kg/plot to kg/ha
round(dat$res1 * 596.6,0)

# Visually.  Note largest positive/negative residuals are adjacent
if(require(desplot)){
  desplot(res1 ~ col + row, dat,
          text=gen, # aspect unknown
          main="ryder.groundnut - residuals")
}

# }
# NOT RUN {
  require(desplot)
  # Swap the dry yields for two plots and re-analyze
  dat[dat$block=="B3" & dat$gen=="A", "dry"] <- 2.8
  dat[dat$block=="B3" & dat$gen=="B", "dry"] <- 1.4
  m2 <- lm(dry~block+gen, dat)
  dat$res2 <- resid(m2)
  desplot(res2 ~ col+row, dat,
          # aspect unknown
          text=gen, main="ryder.groundnut")
# }
# NOT RUN {
# }