agridat (version 1.23)

mead.germination: Seed germination with different temperatures/concentrations

Description

Seed germination with different temperatures/concentrations

Format

A data frame with 64 observations on the following 5 variables.

temp

temperature regimen

rep

replication factor (not blocking)

conc

chemical concentration

germ

number of seeds germinating

seeds

number of seeds tested = 50

Details

The rep factor is NOT a blocking factor.

Used with permission of Roger Mead, Robert Curnow, and Anne Hasted.

References

Schabenberger, O. and Pierce, F.J., 2002. Contemporary statistical models for the plant and soil sciences. CRC.

Examples

if (FALSE) {

library(agridat)

data(mead.germination)
dat <- mead.germination
dat <- transform(dat, concf=factor(conc))
libs(lattice)
xyplot(germ~log(conc+.01)|temp, dat, layout=c(4,1),
       main="mead.germination", ylab="number of seeds germinating")

m1 <- glm(cbind(germ, seeds-germ) ~ 1, dat, family=binomial)
m2 <- glm(cbind(germ, seeds-germ) ~ temp, dat, family=binomial)
m3 <- glm(cbind(germ, seeds-germ) ~ concf, dat, family=binomial)
m4 <- glm(cbind(germ, seeds-germ) ~ temp + concf, dat, family=binomial)
m5 <- glm(cbind(germ, seeds-germ) ~ temp * concf, dat, family=binomial)
anova(m1,m2,m3,m4,m5)
##   Resid. Df Resid. Dev Df Deviance
## 1        63    1193.80
## 2        60     430.11  3   763.69
## 3        60     980.10  0  -549.98
## 4        57     148.11  3   831.99
## 5        48      55.64  9    92.46

# Show logit and fitted values.  T2 has highest germination
subset(cbind(dat, predict(m5), fitted(m5)), rep=="R1")

}