Orthodont {nlme} | R Documentation |

## Growth curve data on an orthdontic measurement

### Description

The `Orthodont`

data frame has 108 rows and 4 columns of the
change in an orthdontic measurement over time for several young subjects.

### Format

This data frame contains the following columns:

- distance
- a numeric vector of distances from the pituitary to the
pterygomaxillary fissure (mm). These distances are measured
on x-ray images of the skull.
- age
- a numeric vector of ages of the subject (yr).
- Subject
- an ordered factor indicating the subject on which the
measurement was made. The levels are labelled
`M01`

to `M16`

for the males and `F01`

to `F13`

for
the females. The ordering is by increasing average distance
within sex.
- Sex
- a factor with levels
`Male`

and
`Female`

### Details

Investigators at the University of North Carolina Dental School
followed the growth of 27 children (16 males, 11 females) from age 8
until age 14. Every two years they measured the distance between the
pituitary and the pterygomaxillary fissure, two points that are easily
identified on x-ray exposures of the side of the head.

### Source

Pinheiro, J. C. and Bates, D. M. (2000), *Mixed-Effects Models in S
and S-PLUS*, Springer, New York. (Appendix A.17)

Potthoff, R. F. and Roy, S. N. (1964), ``A generalized multivariate
analysis of variance model useful especially for growth curve
problems'', *Biometrika*, **51**, 313–326.

### Examples

formula(Orthodont)
plot(Orthodont)

[Package

*nlme* version 3.1-80

Index]