ryder.groundnut {agridat} | R Documentation

## 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.

### Source

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

http://doi.org/10.1017/S0014479700011601

### Examples

    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")

    ## End(Not run)

[Package agridat version 1.16 Index]