BOD {datasets} | R Documentation |
Biochemical Oxygen Demand
Description
The BOD
data frame has 6 rows and 2 columns giving the
biochemical oxygen demand versus time in an evaluation of water
quality.
Usage
BOD
Format
This data frame contains the following columns:
Time
-
A numeric vector giving the time of the measurement (days).
demand
-
A numeric vector giving the biochemical oxygen demand (mg/l).
Source
Bates and Watts (1988, Appendix A1.4)
Originally from Marske (1967), Biochemical Oxygen Demand Data Interpretation Using Sum of Squares Surface M.Sc. Thesis, University of Wisconsin – Madison.
References
Bates DM, Watts DG (1988). Nonlinear Regression Analysis and Its Applications, series Wiley Series in Probability and Statistics. Wiley. ISBN 9780471816430.
Examples
require(stats)
# 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)
fm1
# using the plinear algorithm (trace o/p differs by platform)
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)
[Package datasets version 4.6.0 Index]