Description Usage Format Details Source References Examples

RCB of 12 rice varieties with leafhopper survival

1 | ```
data("gomez.nonnormal3")
``` |

A data frame with 36 observations on the following 3 variables.

`gen`

genotype/variety of rice

`rep`

replicate

`hoppers`

percentage of surviving leafhoppers

For each rice variety, 75 leafhoppers were caged and the percentage of surviving insects was determined.

Gomez suggest replacing 0 values by 1/(4*75) and replacing 100 by 1-1/(4*75) where 75 is the number of insects.

In effect, this means, for example, that (1/4)th of an insect survived.

Because the data are percents, Gomez suggested using the arcsin transformation.

Gomez, K.A. and Gomez, A.A.. 1984,
*Statistical Procedures for Agricultural Research*.
Wiley-Interscience. Page 307.

Used with permission of Kwanchai Gomez.

None.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | ```
data(gomez.nonnormal3)
dat <- gomez.nonnormal3
# First, replace 0, 100 values
dat$thoppers <- dat$hoppers
dat <- transform(dat, thoppers=ifelse(thoppers==0, 1/(4*75), thoppers))
dat <- transform(dat, thoppers=ifelse(thoppers==100, 100-1/(4*75), thoppers))
# Arcsin transformation of percentage p converted to degrees
# is arcsin(sqrt(p))/(pi/2)*90
dat <- transform(dat, thoppers=asin(sqrt(thoppers/100))/(pi/2)*90)
# QQ plots for raw/transformed data
if(require(reshape2) & require(lattice))
qqmath( ~ value|variable, data=melt(dat),
main="gomez.nonnormal3 - raw/transformed QQ plot",
scales=list(relation="free"))
m1 <- lm(thoppers ~ gen, data=dat)
anova(m1) # Match Gomez table 7.25
## Response: thoppers
## Df Sum Sq Mean Sq F value Pr(>F)
## gen 11 16838.7 1530.79 16.502 1.316e-08 ***
## Residuals 24 2226.4 92.77
``` |

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