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, 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

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)
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 )

[Package

*datasets* version 2.2.1

Index]