gomez.multilocsplitplot {agridat} | R Documentation

## Multi-environment trial of rice, split-plot design

### Description

Grain yield was measured at 3 locations with 3 reps per location. Within each rep, the main plot was 6 nitrogen fertilizer treatments and the sub plot was 2 rice varieties.

### Format

A data frame with 108 observations on the following 5 variables.

`loc`

  location, 3 levels

`nitro`

  nitrogen in kg/ha

`rep`

  replicate, 3 levels

`gen`

  genotype, 2 levels

`yield`

  yield, kg/ha

### Source

Gomez, K.A. and Gomez, A.A.. 1984, Statistical Procedures for Agricultural Research. Wiley-Interscience. Page 339.

Used with permission of Kwanchai Gomez.

### Examples

    data(gomez.multilocsplitplot)
    dat <- gomez.multilocsplitplot
    dat$nf <- factor(dat$nitro)

    # Gomez figure 8.3
    require(lattice)
    xyplot(yield~nitro, dat, group=loc, type=c('p','smooth'), auto.key=TRUE,
           main="gomez.multilocsplitplot")

    # AOV
    # Be careful to use the right stratum, 'nf' appears in both strata.
    # Still not quite the same as Gomez table 8.21
    t1 <- terms(yield ~ loc * nf * gen + Error(loc:rep:nf),
                "Error", keep.order=TRUE)
    m1 <- aov(t1, data=dat)
    summary(m1)

    ## Not run:
      # F values are somewhat similar to Gomez Table 8.21
      require(lme4)
      m2 <- lmer(yield ~ loc*nf*gen + (1|loc/rep/nf), dat)
      anova(m2)
      ## Analysis of Variance Table
      ##            Df   Sum Sq  Mean Sq F value
      ## loc         2   117942    58971  0.1525
      ## nf          5 72841432 14568286 37.6777
      ## gen         1  7557570  7557570 19.5460
      ## loc:nf     10 10137188  1013719  2.6218
      ## loc:gen     2  4270469  2135235  5.5223
      ## nf:gen      5  1501767   300353  0.7768
      ## loc:nf:gen 10  1502273   150227  0.3885

    ## End(Not run)

[Package agridat version 1.16 Index]