survsum {survival5} | R Documentation |
Calculates Kaplan-Meier survival percentages, standard error, and number at risk at specified times for defined groups. Test for difference between survival curves.
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",...)
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. |
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.
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. |
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.
Mark Dietrich, Mayo Clinic Section of Medical Research Statistics summer student 1992.