Re: [R] Random Relabelling

From: Kevin Matthews <kevin-matthews_at_uiowa.edu>
Date: Wed, 20 Apr 2011 12:22:54 -0500

I have a map of Iowa of with 4000 locations. At each location, I have a cancer mortality rate. I need to test my null hypothesis; that the spatial distribution of the mortality rates is random. For this test, I need to establish a spatial reference distribution.

My reference distribution will be created by some random relabelling algorithm. The 4000 locations would remain fixed, but the observed mortality rates would be randomly redistributed. Then, I want 1000 permutations of the same algorithm. For each of those 1000 times, I would record the redistributed mortality rate at each location. Then, I would calculate the mean of the 1000 points. The result would be a spatial reference distribution with a mean value of the random permutations at each of the 4000 locations.

Thanks for the response,
Kevin

On Wed, Apr 20, 2011 at 11:08 AM, John Kane <jrkrideau_at_yahoo.ca> wrote:

> Can you explain this a bit more. At the moment I don't see what you are
> trying to achieve. "calculate the mean of the 1000 values at each of the
> 4000 points" does not seem to make sense.
>
> --- On Wed, 4/20/11, kmatthews <kevin-matthews_at_uiowa.edu> wrote:
>
> > From: kmatthews <kevin-matthews_at_uiowa.edu>
> > Subject: [R] Random Relabelling
> > To: r-help_at_r-project.org
> > Received: Wednesday, April 20, 2011, 10:04 AM
> > I have 4000 observations that I need
> > to randomly relabel 1000 times and then
> > calculate the mean of the 1000 values at each of the 4000
> > points. Any ideas
> > for where to begin?
> >
> > Thanks
> > Kevin
> >
>
>

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