Hi,
Please send your information to the r-help list, not just to me, but do
note that the list is plain-text only.
But surely all you are looking for is:
> dt<-c(37,41,40,38,38,37,44,45,48,43,48,46,54,60,32,45,55,62,42,62,62,62,47,42,59,43,60,60,51,43,50,51,47,42,47,51)
> mean(dt)
[1] 48.16667
> sd(dt)/sqrt(length(dt))
[1] 1.404923
I have no idea what bizarre formula SAS uses to calculate standard error,
but the means match.
And you'll note that the lengthy R output you pasted in works just fine,
and *does* include the standard errors and confidence limits *of the
groups you specified* in your formula. Maybe one of the excellent
introduction to R guides available online would be of use to you.
Good luck,
Sarah
On Thu, Oct 20, 2011 at 3:22 PM, Cem Girit <gi...@comcast.net> wrote:
>
> Hello Sarah,
>
>
>
> Thank you for useful reply. I now know how I can search R
> world. Google searchers were not useful.
>
>
>
> I have an efficacy study in which there are 1 control and 3
> treatment groups. The survival event, date of events, and group data are in
> v, d, and g variables (see below). I am using the "Survival" package. In SAS
> it is possible to calculate the mean and standard error of the survival times
> (see an example of SAS output (if it is viewed as html)). I used the
> “survfit” function from this package together with the print or the summary
> options but I could not get any results for these parameters. Although, the
> print function help states that I should get the mean and the error and none
> of the examples in the print.survfit help file worked! I want to calculate
> these two parameters by any means in R. Could you help me on this? Thank you.
>
>
>
> Sincerely,
>
> Cem
>
>
>
> Summary Statistics for Time Variable time
>
>
>
> Mean
>
> Standard Error
>
> 48.2222
>
> 2.6931
>
>
>
> > vT<-c(1,1,1,1,1,1,1,1,0,1,1,1,0,0,1,1,1,0,1,0,0,0,0,1,0,1,0,0,0,1,0,0,1,1,1,0)
>
> > dt<-c(37,41,40,38,38,37,44,45,48,43,48,46,54,60,32,45,55,62,42,62,62,62,47,42,59,43,60,60,51,43,50,51,47,42,47,51)
>
> > gT<-factor(c("Vehicle","Vehicle","Vehicle","Vehicle","Vehicle","Vehicle","Vehicle","Vehicle","Vehicle","DrugA","DrugA","DrugA","DrugA","DrugA","DrugA","DrugA","DrugA","DrugA","DrugB","DrugB","DrugB","DrugB","DrugB","DrugB","DrugB","DrugB","DrugB","DrugC","DrugC","DrugC","DrugC","DrugC","DrugC","DrugC","DrugC","DrugC"))
>
> > fit<-survfit(Surv(dT,vT)~gT)
>
> > fit
>
> Call: survfit(formula = Surv(dT, vT) ~ gtT)
>
>
>
> records n.max n.start events median 0.95LCL 0.95UCL
>
> gtT=DrugA 9 9 9 6 48 45 NA
>
> gtT=DrugB 9 9 9 3 NA 43 NA
>
> gtT=DrugC 9 9 9 4 NA 47 NA
>
> gtT=Vehicle 9 9 9 8 40 38 NA
>
> > print(fit,print.n=getOption("survfit.print.n"),
> > show.rmean=getOption("survfit.print.mean"))
>
> Call: survfit(formula = Surv(dT, vT) ~ gtT)
>
>
>
> records n.max n.start events median 0.95LCL 0.95UCL
>
> gtT=DrugA 9 9 9 6 48 45 NA
>
> gtT=DrugB 9 9 9 3 NA 43 NA
>
> gtT=DrugC 9 9 9 4 NA 47 NA
>
> gtT=Vehicle 9 9 9 8 40 38 NA
>
>
>
> > summary(fit)
>
> Call: survfit(formula = Surv(dT, vT) ~ gtT)
>
>
>
> gtT=DrugA
>
> time n.risk n.event survival std.err lower 95% CI upper 95% CI
>
> 32 9 1 0.889 0.105 0.706 1.000
>
> 43 8 1 0.778 0.139 0.549 1.000
>
> 45 7 1 0.667 0.157 0.420 1.000
>
> 46 6 1 0.556 0.166 0.310 0.997
>
> 48 5 1 0.444 0.166 0.214 0.923
>
> 55 3 1 0.296 0.164 0.100 0.875
>
>
>
> gtT=DrugB
>
> time n.risk n.event survival std.err lower 95% CI upper 95% CI
>
> 42 9 2 0.778 0.139 0.549 1
>
> 43 7 1 0.667 0.157 0.420 1
>
>
>
> gtT=DrugC
>
> time n.risk n.event survival std.err lower 95% CI upper 95% CI
>
> 42 9 1 0.889 0.105 0.706 1.000
>
> 43 8 1 0.778 0.139 0.549 1.000
>
> 47 7 2 0.556 0.166 0.310 0.997
>
>
>
> gtT=Vehicle
>
> time n.risk n.event survival std.err lower 95% CI upper 95% CI
>
> 37 9 2 0.778 0.139 0.5485 1.000
>
> 38 7 2 0.556 0.166 0.3097 0.997
>
> 40 5 1 0.444 0.166 0.2141 0.923
>
> 41 4 1 0.333 0.157 0.1323 0.840
>
> 44 3 1 0.222 0.139 0.0655 0.754
>
> 45 2 1 0.111 0.105 0.0175 0.705
>
>
>
>
>
>
>
> Cem
>
>
>
> Cem Girit
>
>
>
> 56 Marion Drive
>
> Plainsboro, NJ 08536
>
> Tel: (609) 275 0321
>
> Email:gi...@comcast.net
>
> -----Original Message-----
> From: Sarah Goslee [mailto:sarah.gos...@gmail.com]
> Sent: Thursday, October 20, 2011 2:20 PM
> To: Cem Girit
> Cc: r-help@r-project.org
> Subject: Re: [R] Survival analysis
>
>
>
> Hi,
>
>
>
>
>
> On Thu, Oct 20, 2011 at 2:04 PM, Cem Girit <gi...@biopticon.com> wrote:
>
> > Hello,
>
> >
>
> >
>
> >
>
> > I need some results from the survival analysis of my
>
> > data that I do not know whether exist in Survival Package or how to
>
> > obtain if they do:
>
> >
>
> >
>
> >
>
> > 1. The Mean survival time
>
> >
>
> > 2. The standard error of the mean
>
> >
>
> > 3. Point and 95% Lower & Upper Confidence Intervals estimates
>
> >
>
> >
>
> >
>
> > Any help will be greatly appreciated.
>
> >
>
>
>
>
>
> Since we don't know anything about your data or what you've tried, probably
> the best thing for you to do is do some reading on your own, then come back
> to the list when you have a specific question.
>
>
>
> If you go to www.rseek.org and search for survival analysis, you will find a
> great deal of R information on that topic. It's a good place to start.
>
>
>
> Sarah
>
> --
>
> Sarah Goslee
>
> http://www.functionaldiversity.org
--
Sarah Goslee
http://www.stringpage.com
http://www.sarahgoslee.com
http://www.functionaldiversity.org
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
