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 xray 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
toM16
for the males andF01
toF13
for the females. The ordering is by increasing average distance within sex.  Sex

a factor with levels
Male
andFemale
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 xray exposures of the side of the head.
Source
Pinheiro, J. C. and Bates, D. M. (2000), MixedEffects Models in S and SPLUS, 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.
Jose Pinheiro, Douglas Bates, Saikat DebRoy, Deepayan Sarkar and the R Development Core Team (2011). nlme: Linear and Nonlinear Mixed Effects Models. R package version 3.1100. http://CRAN.Rproject.org/package=nlme