This tool is not relevant to my study that examines spatial variations of DOM (dissolved organic matter) and nutrients in streams, but I wanted to learn how it works, so I tried this tool. The result will tell me how clustered my sampling sites are based on the study site extent. I could visually see my sampling sites were clustered within the study site, and the result supported my visual observation. Note, I did not use all of my sampling sites.
Here are some notes:
I project the point Shapefile FIRST. This will determine the units of my results. (I was not sure about this, but I found it was true during the discussion on Monday.)
I used EUCLIDEAN_DISTANCE.
I had to check on “Generate Report” to create a graphical result, which can be accessed from “Results” window –> HTML Report File: NearestNeighbor_Results. I could save this report as PDF.
All the results are in the log/results window. It personally helps me to disable background processing and have an actual log window to obtain a text summary of the results.
Average Nearest Neighbor Summary
Observed Mean Distance: 4318.596812
Expected Mean Distance: 9383.554326
Nearest Neighbor Ratio: 0.460230
z-score: -4.732046
p-value: 0.000002
Unfortunately, I could not easily find a corresponding tool in SSN and STARS. I have to look into their documents.
The linear data (streams) that you’re dealing with definitely makes it harder to analyze for spatial trends. If you haven’t already, you might want to consider looking into creating a cost-distance layer (raster probably?) from which you could run stats. Still wouldn’t be able to use the spatial stats toolbox, I don’t think, but at least you’d be capturing the spatial component in your data. Just a thought 🙂
Kevin,
I have never looked into a cost-distance layer. I have to look into it. Thank you so much for your suggestion!
Peggy
Peggy,
What will your end DOM data look like? Will they be spatial layers or simply numeric values in a spread sheet?
Kate
Kate,
My end DOM data would be a point layer representing how much each DOM source (there will be about 10 different DOM sources, I am assuming at this point) presents at each sampling location. I can turn the point layer into a raster layer. The column fields would be DOM source1, 2, 3,…, etc. Row fields would be location 1, 2, 3, …, etc. And the values show concentrations. Any thoughts?
Peggy