RCB experiment of groundut, wet and dry yields

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.

Source

K. Ryder (1981). Field plans: why the biometrician finds them useful, Experimental Agriculture, 17, 243--256.

https://doi.org/10.1017/S0014479700011601

Examples

# \dontrun{
  
  library(agridat)
  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)
#>  [1] -137  206  -92  -77  132  -32 -191  181 -355   32  167  167 -534  -12 -669
#> [16]  778  152  286 -316 -346  -62  490  296  -62
  
  # Visually.  Note largest positive/negative residuals are adjacent
  libs(desplot)
  desplot(dat, res1 ~ col + row,
          text=gen, # aspect unknown
          main="ryder.groundnut - residuals")
  
  
  libs(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(dat, res2 ~ col+row,
          # aspect unknown
          text=gen, main="ryder.groundnut")

# }