# BOD

##### Biochemical Oxygen Demand

The `BOD`

data frame has 6 rows and 2 columns giving the
biochemical oxygen demand versus time in an evaluation of water
quality.

- Keywords
- datasets

##### 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 -- Madison.

##### Examples

`library(datasets)`

```
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)
```

*Documentation reproduced from package datasets, version 3.1.1, License: Part of R 3.1.1*

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