Leaves: Growth of Leaves

In NRAIA: Data sets from "Nonlinear Regression Analysis and Its Applications"

Description

The Leaves data frame has 15 rows and 2 columns of leaf length over time.

Format

This data frame contains the following columns:

Time

time from initial emergence (days).

Length

leaf length (cm).

Source

Bates and Watts (1998), Nonlinear Regression Analysis and Its Applications, Wiley (Appendix A4.5).

Originally from Heyes and Brown (1956) in F.L. Milthorpe (ed), The Growth of Leaves, London: Butterworth.

Examples

options(show.signif.stars = FALSE)
## first fit a logistic model
fm1 <- nls(Length ~ SSlogis(Time, Asym, xmid, scal), data = Leaves)
summary(fm1)
plotfit(fm1, xlab = "Time from initial emergence (days)",
        ylab = "Leaf length (cm)", main = "Logistic growth model")
## compare with Richards growth model
fm2 <- nls(Length ~ Asym/(1+exp(-(Time - xmid)/scal))^exp(-lpow), Leaves,
           c(coef(fm1),c(lpow = 0)))
summary(fm2)
anova(fm1, fm2)
plotfit(fm2, xlab = "Time from initial emergence (days)",
        ylab = "Leaf length (cm)", main = "Richards growth model")
pm1 <- profile(fm1)
plot(pm1, aspect = 'xy', layout = c(3,1))
plot(pm1, absVal = FALSE, aspect = 'xy', layout = c(3,1))
pm2 <- profile(fm2, alpha = 0.05)
plot(pm2, aspect = 'xy', layout = c(4,1))
plot(pm2, absVal = FALSE, aspect = 'xy', layout = c(4,1))

NRAIA documentation built on May 2, 2019, 4:52 p.m.