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Ginny
(Stranger )
07/02/07 09:22 PM
 Want a challenge? Help needed for dolphin analysis

My GIS experience is limited but I have ArcGIS 9. I'm trying to figure out how to analyze some spinner dolphin data, looking at whether individuals within dolphin groups are closer together over different seafloor substrates. I have digitized x, y locations (not GPS) and substrate info (for each dolphin in 32 different dolphin groups) in MS Excel columns. I thought nearest neighbor analysis might work for me to determine:

1. If groups are closer together depending on substrate.

If that works out, then...

2. If that varies with whether a calf is present in the group (and maybe # of calves within a group).

3. If that varies with total group size or number of non-mother adults.

If anyone out there knows if this is something that I can do or has other ideas on how to get those results, and how to get started, I'd be a happy woman!

Thank you, Ginny

robbo
(Stranger )
07/12/07 01:26 AM
 Re: Want a challenge? Help needed for dolphin ana [re: Ginny]

Hi Ginny,

In general terms, the task you want to do is almost certainly best done through GIS. It all depends how involved you want to get in terms of the analysis, but it sounds like you're on the right track.

I would look at, for one substrate at a time, using ArcGIS to work out the average distance between points (dolphin groups), rather than nearest neighbour, I guess as it could be skewed otherwise and not represent the overall degree of 'closeness'.

If you wanted to do it more fully from there, then look at doing some correlation on the results, to look for any statistical significance, and the various conditions you state. Particularly the stat work will help identify trends based on group composition. Its been a while since I did something like that in ArcGIS, but the Spatial Analyst & Geostatistical Analyst extensions should be able to do all you want, if you have access to them. How scientific you go I guess depends on whether your project is commercial, private, or academic!

You may also have some joy asking at the user forums at http://support.esri.com/ and/or having a look at any custom functions people have posted there that may help, a search on 'dolphins' over there shows some posts.

Hope that helps, if you need any particular pointers about getting started, post back.

Regards,

Rob

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