

survsum(survival5)                           R Documentation

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_T_i_m_e_s

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

     Calculates Kaplan-Meier survival percentages, standard
     error, and number at risk at specified times for
     defined groups.  Test for difference between survival
     curves.

_U_s_a_g_e_:

     survsum(formula, data=sys.parent(), sptms=NULL, xlim,
     tlines=T, log=F, xscale=1,yscale=100, mark.time=F, mark=3,
     cex=1, xlab="Time", ylab="Survival (%)", lgd="bl",
     ttl="K-M Survival",...)

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

 formula: a formula expression as for other survival models,
          of the  form `Surv(time,  status) ~ predictors'.
          Same formula expression as used in `survfit'. See
          help file for survfit.  Maximum of 6 groups.

    data: a data.frame in which to interpret the variables
          named in the formula.

   sptms: a specified vector of positive times at which to
          compute the survival percentages, standard errors,
          and numbers at risk.  A maximum of four times can
          be specified.

    xlim: a vector of the form: `c(x1,x2)'.  The approximate
          minimum and maximum values to  be  put  on  x-
          axis.  Default sets x1=0 and x2=maximum time
          value.

  tlines: a logical value indicating whether vertical lines
          and labels should be drawn on the plot at the
          specified times.

     log: logical value: should the y axis be on a log
          scale?

  xscale: a scalar to be used to divide the x axis.  A value
          of 365, for instance, would be used to convert
          from days to years.

  yscale: a scalar to be used to multiply the y axis.  The
          default value of 100 is used to get a percent
          scale.  `yscale=1' would set the y axis from 0 to
          1.

mark.time: controls the labeling of the curves.  If set to
          True then curves are marked at each censoring
          time.  If `mark.time' is a numeric vector, then
          curves are marked at these specified time points.

    mark: vector of mark parameters, which will be used to
          label the  curves.  The `lines' help file contains
          examples of the possible marks.  The vector is
          reused cyclically if it  is shorter than the num-
          ber of curves.

     cex: parameter available to change the size of `mark'.
          Not a vector; all marks have the same size.

    xlab: character string label for the x axis.

    ylab: character string label for the y axis.

     lgd: legend placement.  `"tr"'=top right corner of the
          plot, `"under"'=under the plot, `"n"' omits the
          legend.  The default is: `"bl"'=bottom left corner
          of the plot.

     ttl: title to be printed in the center top.

     ...: In addition, the high-level graphics arguments
          described under par and the arguments to title may
          be supplied to this function.

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

     The total number of points and events is reported for
     each group.  For each specified time point, group sur-
     vival percentages (followed by standard error and num-
     ber left at risk) are computed.

     The test for a difference between survival curves uses
     the chisquare statistic from the `survdiff' function
     with `rho=0'.  This is the log-rank test.

_V_a_l_u_e_:

     A list of class `"htest"', containing the following
     components:

  no.pts: the total number of data points in each group.

no.events: the total number of events in each group.

   chisq: the chisquare statistic for the test of a differ-
          ence between survival curves.

       p: the p-value for the above test.

      t1: a matrix containing the survival percentages,
          standard errors, and numbers at risk for all
          groups at time t1.

t2,t3,t4: see above.

_S_i_d_e _E_f_f_e_c_t_s_:

     A plot with multiple survival curves is drawn (one for
     each group). This plot includes: overall group statis-
     tics and group statistics at each specified time point
     and a test for a difference between survival curves.

_A_u_t_h_o_r_(_s_)_:

     Mark Dietrich, Mayo Clinic Section of Medical Research
     Statistics summer student 1992.

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

