[R] sample size estimation for count (poisson?) data?

David Winsemius dwinsemius at comcast.net
Thu Nov 13 00:41:00 CET 2008

The first hit for search on "sample size" and "poisson" on Baron's  
search engine web interface appears on target:


Getting the same result from your console window requires a couple of  
extra back-slashes:

 > RSiteSearch(""sample size" poisson")
Error: syntax error
 > RSiteSearch("\"sample size\" poisson")
A search query has been submitted to http://search.r-project.org
The results page should open in your browser shortly.

David Winsemius
Heritage Labs

On Nov 12, 2008, at 2:46 PM, Shawn Morrison wrote:

> Is there a function in R that will allow me to estimate the sample
> size required from count data (poisson data?), given the known
> variance and desired margin of error and confidence interval?
> My specific data set will be based on a survey of hikers that will be
> asked about the number of animals of species 'x' they observed during
> a given period. I need to know the number of hikers to interview. ie,
> I would like to calculate the mean number of species 'x' +/- margin of
> error with 95% confidence.
> This is a simple exercise for normally distributed continuous data,
> but I'm running into roadblocks for count data.
> Sincerely,
> Shawn Morrison
> 	[[alternative HTML version deleted]]
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