Description Usage Format Details Source References Examples

RCB experiment of rice, 12 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.

Used with permission of Kwanchai Gomez.

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

None.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | ```
## Not run:
library(agridat)
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
libs(reshape2, 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
## End(Not run)
``` |

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