+-------+-------------------+
| BOD   | 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, D.M. and Watts, D.G. (1988), *Nonlinear Regression Analysis and
Its Applications*, Wiley, Appendix A1.4.

Originally from Marske (1967), *Biochemical Oxygen Demand Data
Interpretation Using Sum of Squares Surface* M.Sc. Thesis, University of
Wisconsin â€“ Madison.

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
    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)

