Orthodont data frame has 108 rows and 4 columns of the
change in an orthdontic measurement over time for several young subjects.
This data frame contains the following columns:
a numeric vector of distances from the pituitary to the pterygomaxillary fissure (mm). These distances are measured on x-ray images of the skull.
a numeric vector of ages of the subject (yr).
an ordered factor indicating the subject on which the
measurement was made. The levels are labelled
M16 for the males and
the females. The ordering is by increasing average distance
a factor with levels
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.
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.
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 3.1-100. http://CRAN.R-project.org/package=nlme