survsum              package:survival5              R Documentation

_K_a_p_l_a_n-_M_e_i_e_r _S_u_r_v_i_v_a_l _C_u_r_v_e _a_n_d _P_e_r_c_e_n_t_a_g_e_s _a_t _S_e_l_e_c_t_e_d _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 number 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 survival percentages
     (followed by standard error and number 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 difference 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 statistics 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:

