CO2 {datasets} | R Documentation |
The CO2
data frame has 84 rows and 5 columns of data from an
experiment on the cold tolerance of the grass species
Echinochloa crus-galli.
CO2
This data frame contains the following columns:
Qn1
< Qn2
< Qn3
< ... < Mc1
giving a unique identifier for each plant.
Quebec
Mississippi
giving the origin of the plant
nonchilled
chilled
The CO2 uptake of six plants from Quebec and six plants from Mississippi was measured at several levels of ambient CO2 concentration. Half the plants of each type were chilled overnight before the experiment was conducted.
Potvin, C., Lechowicz, M. J. and Tardif, S. (1990) “The statistical analysis of ecophysiological response curves obtained from experiments involving repeated measures”, Ecology, 71, 1389–1400.
Pinheiro, J. C. and Bates, D. M. (2000) Mixed-effects Models in S and S-PLUS, Springer.
require(stats) coplot(uptake ~ conc | Plant, data = CO2, show = FALSE, type = "b") ## fit the data for the first plant fm1 <- nls(uptake ~ SSasymp(conc, Asym, lrc, c0), data = CO2, subset = Plant == 'Qn1') summary(fm1) ## fit each plant separately fmlist <- list() for (pp in levels(CO2$Plant)) { fmlist[[pp]] <- nls(uptake ~ SSasymp(conc, Asym, lrc, c0), data = CO2, subset = Plant == pp) } ## check the coefficients by plant sapply(fmlist, coef)