# BodyWeight: Rat weight over time for different diets In MEMSS: Data Sets from Mixed-Effects Models in S

## Description

The BodyWeight data frame has 176 rows and 4 columns.

## Format

This data frame contains the following columns:

weight

a numeric vector giving the body weight of the rat (grams).

Time

a numeric vector giving the time at which the measurement is made (days).

Rat

an factor with levels A to P identifying the rat whose weight is measured.

Diet

a factor with levels a to c indicating the diet that the rat receives.

## Details

Hand and Crowder (1996) describe data on the body weights of rats measured over 64 days. These data also appear in Table 2.4 of Crowder and Hand (1990). The body weights of the rats (in grams) are measured on day 1 and every seven days thereafter until day 64, with an extra measurement on day 44. The experiment started several weeks before “day 1.” There are three groups of rats, each on a different diet.

## Source

Pinheiro, J. C. and Bates, D. M. (2000), Mixed-Effects Models in S and S-PLUS, Springer, New York. (Appendix A.3)

Crowder, M. and Hand, D. (1990), Analysis of Repeated Measures, Chapman and Hall, London.

Hand, D. and Crowder, M. (1996), Practical Longitudinal Data Analysis, Chapman and Hall, London.

## Examples

 1 str(BodyWeight)

### Example output

Attaching package: 'MEMSS'

The following objects are masked from 'package:datasets':

CO2, Orange, Theoph

'data.frame':	176 obs. of  4 variables:
\$ weight: num  240 250 255 260 262 258 266 266 265 272 ...
\$ Time  : num  1 8 15 22 29 36 43 44 50 57 ...
\$ Rat   : Factor w/ 16 levels "A","B","C","D",..: 1 1 1 1 1 1 1 1 1 1 ...
\$ Diet  : Factor w/ 3 levels "a","b","c": 1 1 1 1 1 1 1 1 1 1 ...

MEMSS documentation built on May 2, 2019, 1:05 p.m.