R help - Dec 2011 - Resampling with replacement on a binary (0, 1) dataset to get Cis

...is it possible to do that?

I apologize for something that must be a very trivial question for most of
you but, unfortunately, it is not for me.
A binary variable is measured, say, 50 times each year during 10 year. My
interest is focused on the percentage of 1s with respect to the total if
each year.
There is no way to repeat those measure within each year and getting the CIs
by the "normal way".
By the way, it would be important to get even a rough estimate of the CIs of
these estimates (/n/1//n/1+/n/0).

In case this is not a blasphemy, how might be done in R?

Thanks in advance for any help

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On Dec 1, 2011, at 6:34 AM, lincoln wrote:
> ...is it possible to do that?
>
> I apologize for something that must be a very trivial question for  
> most of
> you but, unfortunately, it is not for me.
> A binary variable is measured, say, 50 times each year during 10  
> year. My
> interest is focused on the percentage of 1s with respect to the  
> total if
> each year.
> There is no way to repeat those measure within each year and getting  
> the CIs
> by the "normal way".
> By the way, it would be important to get even a rough estimate of  
> the CIs of
> these estimates (/n/1//n/1+/n/0).
>
> In case this is not a blasphemy, how might be done in R?
?prop.test
>
> Thanks in advance for any help
>
David Winsemius, MD
West Hartford, CT

Thanks.

So, suppose for one specific year (first year over 10) the percentage of
successes deriving from 100 trials with 38 successes (and 62 failures), its
value would be 38/100=0.38.
I could calculate its confidence intervals this way:
> success<-38
> total<-100
> prop.test(success,total,p=0.5,alternative="two.sided")
	1-sample proportions test with continuity
	correction

data:  success out of total, null probability 0.5 
X-squared = 5.29, df = 1, p-value = 0.02145
alternative hypothesis: true p is not equal to 0.5 
95 percent confidence interval:
 0.2863947 0.4829411 
sample estimates:
   p 
0.38 

So it would be var$1=0.38 , CI=0.286-0.483

Is it correct?

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