Re: st: Survival analysis - individual survival functions

[Steven Samuels <sjsamuels@gmail.com>]

Paul,

 -predict- gives values at the observations after every regression  
command. To get it for arbitrary values of the inputs, you have to do  
it yourself.   S(t| t_0) = S(t)/S(t_0), and the formulas for S(.) are  
on page 358 of the Stata Manual (V 11).  You can get the linear  
predictor for any values of the X's with  -margins-  or -adjust- 
( Stata<11).  Add the appropriate auxiliary parameters (returned  
results e(theta), e(aux_p), e(gamma), e(sigma), e(kappa)); your t and  
t_0; then plug  everything into the formulas.

Steve

Steven J. Samuels
sjsamuels@gmail.com
18 Cantine's Island
Saugerties NY 12477
USA
Voice: 845-246-0774
Fax:    206-202-4783

On Dec 15, 2010, at 4:25 PM, Seed, Paul wrote:

Dear all,
Following a parametric survival regression,
I can use -predict- with the -surv- option to get
the survival function; but I only do not seem to have
any choice over when it is calculated for.

The help file promises me values for S(t|t_0),
and I would like to set both t and t_0 myself.
But they seem to be set automatically,
at the time of entry and exit of the subject.

Is there a simple way of doing this?
If not, is there any chance of it being included
in a future version of Stata?

Many thanks.


Paul Seed, Senior Lecturer in Medical Statistics,
020 7188 3642,
paul.seed@kcl.ac.uk,
King's College London, Division of Women's Health
Please do not send unencrypted un-anonymised data to this address.




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