BOD {nls} | R Documentation |
The BOD
data frame has 6 rows and 2 columns giving the
biochemical oxygen demand versus time in an evaluation of water quality.
Time |
A numeric vector giving the time of the measurement (days). |
demand |
A numeric vector giving the biochemical oxygen demand (mg/l). |
This data frame contains the following columns:
Bates, D.M. and Watts, D.G. (1988), Nonlinear Regression Analysis and Its Applications, Wiley, Appendix A1.4.
Originally from Marske (1967), M.Sc. Thesis, University of Wisconsin Madison.
library(nls) data(BOD) # simplest form of fitting a first-order model to these data fm1 <- nls(demand ~ A*(1-exp(-exp(lrc)*Time)), data = BOD, start = c(A = 20, lrc = log(.35))) coef(fm1) print(fm1) # using the plinear algorithm fm2 <- nls(demand ~ (1-exp(-exp(lrc)*Time)), data = BOD, start = c(lrc = log(.35)), algorithm = "plinear", trace = TRUE) # using a self-starting model fm3 <- nls(demand ~ SSasympOrig(Time, A, lrc), data = BOD) summary( fm3 )