Orthodont                package:nlme                R Documentation

_G_r_o_w_t_h _c_u_r_v_e _d_a_t_a _o_n _a_n _o_r_t_h_d_o_n_t_i_c _m_e_a_s_u_r_e_m_e_n_t

_D_e_s_c_r_i_p_t_i_o_n:

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

_F_o_r_m_a_t:

     This data frame contains the following columns:

     _d_i_s_t_a_n_c_e 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_g_e a numeric vector of ages of the subject (yr).

     _S_u_b_j_e_c_t 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.

     _S_e_x a factor with levels `Male' and `Female' 

_D_e_t_a_i_l_s:

     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.

_S_o_u_r_c_e:

     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.

_E_x_a_m_p_l_e_s:

     data(Orthodont)
     coplot(distance ~ age | Subject, data = Orthodont, show = FALSE)

