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)
     formula(Orthodont)
     plot(Orthodont)

