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.

Source

Roger Mead, Robert N Curnow, Anne M Hasted. 2002. Statistical Methods in Agriculture and Experimental Biology, 3rd ed. Chapman and Hall. Page 350-351.

References

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

Examples

if (FALSE) { # \dontrun{

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")

} # }