allcroft.lodging {agridat} | R Documentation

## Multi-environment trial of cereal with lodging data

### Description

Percent lodging is given for 32 genotypes at 7 environments.

### Format

A data frame with 224 observations on the following 3 variables.

`env`

  environment, 1-7

`gen`

  genotype, 1-32

`y`

  percent lodged

### Details

This data is for the first year of a three-year study.

### Source

D. J. Allcroft and C. A. Glasbey, 2003. Analysis of crop lodging using a latent variable model. Journal of Agricultural Science, 140, 383–393. http://doi.org/10.1017/S0021859603003332

Used with permission of Chris Glasbey.

### Examples

    data("allcroft.lodging")
    dat <- allcroft.lodging

    # Transformation
    dat$sy <- sqrt(dat$y)
    # Variety 4 has no lodging anywhere, so add a small amount
    dat[dat$env=='E5' & dat$gen=='G04',]$sy <- .01

    require(lattice)
    dotplot(env~y|gen, dat, as.table=TRUE,
            xlab="Percent lodged (by genotype)", ylab="Variety",
            main="allcroft.lodging")

    # Tobit model
    if(require(AER)){
      m3 <- tobit(sy ~ 1 + gen + env, left=0, right=100, data=dat)

      # Table 2 trial/variety means
      preds <- expand.grid(gen=levels(dat$gen), env=levels(dat$env))
      preds$pred <- predict(m3, newdata=preds)
      round(tapply(preds$pred, preds$gen, mean),2)
      round(tapply(preds$pred, preds$env, mean),2)

    }

[Package agridat version 1.16 Index]