Loblolly              package:datasets              R Documentation

_G_r_o_w_t_h _o_f _L_o_b_l_o_l_l_y _p_i_n_e _t_r_e_e_s

_D_e_s_c_r_i_p_t_i_o_n:

     The 'Loblolly' data frame has 84 rows and 3 columns of records of
     the growth of Loblolly pine trees.

_U_s_a_g_e:

     Loblolly

_F_o_r_m_a_t:

     This data frame contains the following columns:

     _h_e_i_g_h_t a numeric vector of tree heights (ft).

     _a_g_e a numeric vector of tree ages (yr).

     _S_e_e_d an ordered factor indicating the seed source for the tree.
          The ordering is according to increasing maximum height.


_S_o_u_r_c_e:

     Kung, F. H. (1986), Fitting logistic growth curve with
     predetermined carrying capacity, in _Proceedings of the
     Statistical Computing Section, American Statistical Association_,
     340-343.

     Pinheiro, J. C. and Bates, D. M. (2000) _Mixed-effects Models in S
     and S-PLUS_, Springer.

_E_x_a_m_p_l_e_s:

     require(stats); require(graphics)
     plot(height ~ age, data = Loblolly, subset = Seed == 329,
          xlab = "Tree age (yr)", las = 1,
          ylab = "Tree height (ft)",
          main = "Loblolly data and fitted curve (Seed 329 only)")
     fm1 <- nls(height ~ SSasymp(age, Asym, R0, lrc),
                data = Loblolly, subset = Seed == 329)
     summary(fm1)
     age <- seq(0, 30, length.out = 101)
     lines(age, predict(fm1, list(age = age)))

