ppoints                 package:base                 R Documentation

_O_r_d_i_n_a_t_e_s _f_o_r _P_r_o_b_a_b_i_l_i_t_y _P_l_o_t_t_i_n_g

_D_e_s_c_r_i_p_t_i_o_n:

     Generates the sequence of ``probability'' points `(1:m - a)/(m +
     (1-a)-a)' where `m' is either `n', if `length(n)==1', or
     `length(n)'.

_U_s_a_g_e:

     ppoints(n, a = ifelse(n <= 10, 3/8, 1/2))

_D_e_t_a_i_l_s:

     If 0 < a < 1, the resulting values are within (0,1) (excluding
     boundaries). In any case, the resulting sequence is symmetric in
     [0,1], i.e., `p + rev(p) == 1'.

     `ppoints()' is used in `qqplot' and `qqnorm' to generate the set
     of probabilities at which to evaluate the inverse distribution.

_S_e_e _A_l_s_o:

     `qqplot', `qqnorm'.

_E_x_a_m_p_l_e_s:

     ppoints(4) # the same as  ppoints(1:4)
     ppoints(10)
     ppoints(10, a=1/2)

