Seed germination with different temperatures/concentrations
Seed germination with different temperatures/concentrations
A data frame with 64 observations on the following 5 variables.
temptemperature regimen
repreplication factor (not blocking)
concchemical concentration
germnumber of seeds germinating
seedsnumber of seeds tested = 50
The rep factor is NOT a blocking factor.
Used with permission of Roger Mead, Robert Curnow, and Anne Hasted.
Roger Mead, Robert N Curnow, Anne M Hasted. 2002. Statistical Methods in Agriculture and Experimental Biology, 3rd ed. Chapman and Hall. Page 350-351.
Schabenberger, O. and Pierce, F.J., 2002. Contemporary statistical models for the plant and soil sciences. CRC.
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")Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.