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R: st: bootstrapping probabilities


From   "Carlo Lazzaro" <[email protected]>
To   <[email protected]>
Subject   R: st: bootstrapping probabilities
Date   Sun, 8 Apr 2007 09:03:47 +0200

Dear Maartin thanks a lot for Your Kind answer.

I was actually inaccurate in oulining the problem I have faced.

I was dealing with model aimed at comparing two healthcare programmes (A and
B; 255 observations each) in terms of their effectiveness. 
I cannot rely on a dataset, but only on a point estimates for A and B
effectiveness, coming from a clinical trial (programme A=88,89%; programme
B= 79,76%; difference=9,13%).

Lacking other hypotheses, I assumed that, for both programmes, the
effectiveness followed a multivariate normality, and this was the original
mistake, because some values exceed the 0-1 range. So, Maartin is right in
highlighting that this was not a bootstrap problem: by the way, may I ask
Maartin and All the Statalisters some hints to tackle this issue with Stata
9.2?

Thanks a lot for Your Kindness and for Your time.

Kind Regards,

Carlo



-----Messaggio originale-----
Da: [email protected]
[mailto:[email protected]] Per conto di Maarten buis
Inviato: sabato 7 aprile 2007 23.18
A: [email protected]
Oggetto: Re: st: bootstrapping probabilities

--- Carlo Lazzaro <[email protected]> wrote:
> I would like to bootstrap a probability sample. How can I impose that
> each bootstrap sample should not exceed the 0-1 range?

I don't understand the problem. Does the probability refer the
probability that a case is in your sample or is it a variable? In
either case they are usually given, so if they are in the 0-1 range in
the original data, they will also be so in the bootstrap sample. Even
if you wanted to recompute them in each bootstrap sample, the method of
computing the probabilities should ensure that they are in the 0-1
range, so if it is not than it is not a bootstrap problem. So tell us:
a) what are these probabilities, and  b) how are they computed.
Best,
Maarten 

-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


		
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