little.splitblock {agridat} | R Documentation

## Split-block experiment of sugar beets

### Description

Split-block experiment of sugar beets.

### Usage

    data("little.splitblock")

### Format

A data frame with 80 observations on the following 6 variables.

`row`

  row

`col`

  column

`yield`

  sugar beet yield, tons/acre

`harvest`

  harvest date, weeks after planting

`nitro`

  nitrogen, pounds/acre

`block`

  block

### Details

Four rates of nitrogen, laid out as a 4x4 Latin-square experiment.

Within each column block, the sub-plots are strips (across 4 rows) of 5 different harvest dates.

The use of sub-plots a s strips necessitates care when determining the error terms in the ANOVA table.

Note, Little has yield value of 22.3 for row 3, column I-H3. This data uses 23.3 in order to match the marginal totals given by Little.

### Source

Thomas M. Little, F. Jackson Hills. (1978) Agricultural Experimentation

### References

None.

### Examples

    data(little.splitblock)
    dat <- little.splitblock

    # Match marginal totals given by Little.
    ## sum(dat$yield)
    ## with(dat, tapply(yield,col,sum))
    ## with(dat, tapply(yield,row,sum))

    # Layout shown by Little figure 10.2
    if(require(desplot)){
      desplot(yield ~ col*row, data=dat,
              out1=block, out2=col, col=nitro, cex=1, num=harvest,
              main="little.splitblock")
    }

    # Convert continuous traits to factors
    dat <- transform(dat, R=factor(row), C=factor(block),
                     H=factor(harvest), N=factor(nitro))

    if(FALSE){
      library(lattice)
      xyplot(yield ~ nitro|H,dat)
      xyplot(yield ~ harvest|N,dat)
    }

    # Anova table matches Little, table 10.3
    m1 <- aov(yield ~ R + C + N + H + N:H +
                Error(R:C:N + C:H + C:N:H), data=dat)
    summary(m1)

[Package agridat version 1.16 Index]