[R] Help for survival curves for the survfit object‏

Göran Broström goran.brostrom at umu.se
Mon Feb 8 16:18:39 CET 2016

On 2016-02-08 14:11, 于慧琳 wrote:
> Hi guy,I have some problems when plotting survival curves for the
> survfit object.My survfit model is as
> follows:fit6<-survfit(Surv(Survival_time_year_,event)~Race_1_Desc,data=data6)Race_1_Desc
> is a indicator variable which has 0 and 1 values.However, in my
> dataset, all of the Race_1_Desc are of value 0, which means I have
> only 1 group.When I plot my survival curve use the following
> command,plot(fit6,col=c("blue","red"),xlab="Survival
> Time",ylab="Survival Probability",main="Survival Plot for Leaf 6")
> It is correct that I only has one curve for Race_1_Desc coded as 0,
> which is the blue full line. But there are also two dashed line, one
> is red and one is blue.I just want to know what are the two dashed
> lines mean and why the show up in the plot.

Maybe they are confidence limits? Read the help page for plot.survfit, 
especially 'conf.int'.


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