

janka(Rnotes)                                R Documentation

_T_h_e _J_a_n_k_a _h_a_r_d_n_e_s_s _d_a_t_a

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

     Janka hardness is an important structural property of
     Australian timbers, but is difficult to measure
     directly. It is, however, directly related to the den-
     sity of the timber which is relatively easy to measure.
     In an effort to develop a method of predicting Janka
     hardness from density, the Janka hardness (here consid-
     ered the response) and the density of 36 Australian
     eucalypt hardwoods was measured.

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

     The data frame `janka' has two components: `dens' is
     the timber density for the tree and `hard' is the cor-
     responding Janka hardness.

     A low-degree polynomial regression may be an appropri-
     ate model. A log or square-root transformation of hard-
     ness may also be useful.

_C_A_T_E_G_O_R_Y_:

     Polynomial regression.  Transformations.

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

     E. J. Williams, Regression Analysis, Wiley, 1959

