qqmath                package:lattice                R Documentation

_Q-_Q _P_l_o_t _w_i_t_h _T_h_e_o_r_e_t_i_c_a_l _D_i_s_t_r_i_b_u_t_i_o_n

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

     Quantile-Quantile plot of a sample and a theoretical distribution

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

     qqmath(formula, distribution = qnorm, f.value = NULL, ...)

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

 formula: formula of the form '~ x | g1 * g2 * ...', where 'x' must be
          a numeric. 

distribution: a quantile function that takes a vector of probabilities
          as argument and produces the corresponding quantiles.
          Possible values are 'qnorm,qunif' etc. Distributions with
          other required arguments need to be passed in as user defined
          functions. This is also passed in as an argument to the panel
          function (though not used by the default panel function), 
          and the prepanel function if specified, for use in the bery
          commonly used '(pre)panel.qqmathline'. 

 f.value: optional function of a single integer (representing sample
          size), returning a vector of probabilities corresponding to
          which quantiles should be plotted. The typical value for this
          argument is 'ppoints', which is also the S-PLUS default. If
          specified, the probabilities generated by this function is
          used for the plotted quantiles, using the 'quantile' function
          for the sample, and the 'distribution' argument for the
          theoretical distribution.

          'f.value' defaults to 'NULL', which has the effect of using
          'ppoints' for the quantiles of the theoretical distribution,
          but the exact data values for the sample. This is similar to
          what happens for 'qqnorm'.

     ...: Other arguments

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

     'qqmath' produces a Q-Q plot of the given sample and a theoretical
     distribution.  The default behaviour of 'qqmath' is different from
     the corresponding S-PLUS function, but is similar to 'qqnorm'. See
     the entry for 'f.value' for specifics.

     This and all other high level Trellis functions have several
     arguments in common. These are extensively documented only in the
     help page for 'xyplot', which should be consulted to learn more
     detailed usage.

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

     An object of class ``trellis''. The `update' method can be used to
     update components of the object and the `print' method (usually
     called by default) will plot it on an appropriate plotting device.

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

     Deepayan Sarkar <URL: deepayan@stat.wisc.edu>

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

     'xyplot', 'panel.qqmath', 'panel.qqmathline',
     'prepanel.qqmathline', 'Lattice', 'quantile'

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

     qqmath(~ rnorm(100), distribution = function(p) qt(p, df = 10))
     qqmath(~ height | voice.part, aspect = 1, data = singer,
            prepanel = prepanel.qqmathline,
            panel = function(x, y) {
               panel.qqmathline(y, distribution = qnorm)
               panel.qqmath(x, y)
            })

