gomez.nonnormal2 {agridat} | R Documentation

## RCB trial of rice measuring white heads

### Description

RCB trial of rice measuring white heads

### Usage

    data("gomez.nonnormal2")

### Format

A data frame with 42 observations on the following 3 variables.

`gen`

  genotype

`rep`

  replicate

`white`

  percentage of white heads

### Details

The data are the percent of white heads from a rice variety trial of 14 varieties with 3 reps. Because many of the values are less than 10, the suggested data transformation is sqrt(x+.5).

### Source

Gomez, K.A. and Gomez, A.A.. 1984, Statistical Procedures for Agricultural Research. Wiley-Interscience. Page 300.

Used with permission of Kwanchai Gomez.

### References

None.

### Examples

    data(gomez.nonnormal2)
    dat <- gomez.nonnormal2

    # Gomez suggested sqrt transform
    dat <- transform(dat, twhite = sqrt(white+.5))

    # QQ plots for raw/transformed data
    if(require(reshape2) & require(lattice))
      qqmath( ~ value|variable, data=melt(dat),
             main="gomez.nonnormal2 - raw/transformed QQ plot",
             scales=list(relation="free"))

    # Gomez anova table 7.21
    m1 <- lm(twhite ~ rep + gen, data=dat)
    anova(m1)
    ## Response: twhite2
    ##           Df Sum Sq Mean Sq F value    Pr(>F)
    ## rep        2  2.401  1.2004  1.9137    0.1678
    ## gen       13 48.011  3.6931  5.8877 6.366e-05 ***
    ## Residuals 26 16.309  0.6273

[Package agridat version 1.16 Index]