symbox                  package:car                  R Documentation

_B_o_x_p_l_o_t_s _f_o_r _t_r_a_n_s_f_o_r_m_a_t_i_o_n_s _t_o _s_y_m_m_e_t_r_y

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

     'symbox' first transforms 'x' to each of a series of selected
     powers, with each transformation standardized to mean 0 and
     standard deviation 1. The results are then displayed side-by-side
     in boxplots, permiting a visual assessment of which power makes
     the distribution reasonably symmetric.

_U_s_a_g_e:

     symbox(x, powers=c(-1, -.5, 0, .5, 1), start=0)

_A_r_g_u_m_e_n_t_s:

       x: a numeric vector.

  powers: a vector of selected powers to which 'x' is to be raised.  A
          power of 0 is taken to mean $log(x)$. Negative powers are
          taken to mean $-x^p$, to preserve the order of the data. For
          meaningful comparison of powers,  1 should be included in the
          vector of powers.

   start: a constant to be added to 'x'; after adding the start, all
          data values must be positive.

_V_a_l_u_e:

     as returned by 'boxplot'.

_A_u_t_h_o_r(_s):

     Gregor Gorjanc, John Fox jfox@mcmaster.ca

_R_e_f_e_r_e_n_c_e_s:

     Friendly, M. (2005) _SAS System for Statistical Graphics, 2nd
     Edition._  SAS Institute (In preparation).

_S_e_e _A_l_s_o:

     'boxplot', 'boxcox', 'box.cox'

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

     symbox(Prestige$income)

