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I am relatively new to ArcGIS.

I have point data of specific locations (e.g. doctor’s surgeries). I have buffer rings around these points of 0.5 miles (roughly 10 mins walking).

I want to calculate the percentage of my surgeries which are in a cluster where there are 3 or more surgeries within 0.5 miles (as the crow flies).

What is the best tool to calculate this?

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    Are the buffer rings exclusive, ie do you only want to cluster within the buffer. What if 3 points are less than .5 miles apart but one of them exists in one buffer area and two of them in the other area, are those considered a cluster? – ed.hank Jul 29 '16 at 14:55
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From what I'm seeing you seem to already have the clusters. If there are arranged in points then follow the instructions here:

This will give you the number of points inside each buffer

Then simply open the field where your sums are located and create a new Float field. Then using the field calculator enter the percentage (sum/number of total surgeries)*100

This is what it should look like when you enter it

And that's all there is to it.

Forgive me if I'm not understanding but just from a data stand point, I think there might be an issue if there are overlapping buffers and points are being counted twice. Not so much that it will throw the percents off, but the fact is the theoretical patient didn't go to two hospitals, they only went to 1...So individually your percent might be correct but comparatively they will be off.

Solution?

Clip overlapping polygons. There's plenty of ways to do this that are just a google away.

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