Value units kernel density?

Question

I am trying to display the coordinates I collected of sperm whales I found during my research in Northern Norway, using the kernel tool to show the density within the area. General info: total amount of whales found 141, so 141 different coordinates, output cell size is 50 and area units default, so square kilometers.

The values I get from the kernel density are now between 0 - 2.7. Does that mean a maximum of 2.7 sperm whales per km² were found (so the highest aggregation on the map)? When I zoom in closer to the area where most whales were found, so between 2.4 - 2.7 according to the values, I count 5 individuals?

I read through earlier posts and other websites but couldn't find the answer I am looking for.

Thanks,

Saskia

AmyNewsam · Answer

Hey Dan, I'm having the same trouble understanding the units of a kernel density.  The first output below is for 0.1 cell output size, 2 meter search radius, and area units square meters.  The second is the same except for using a 1 m search radius.  Symbology is quartiles for both.  I would expect the values to mean predicted points per unit of area, but then shouldn't I expect to see the values scale between the two outputs by the same value for each bin?

DanPatterson_Retired · Answer

ratios... if you found 1 object in 1 km^2 that is the same as having a density of 1/km^2 or 1/(1000*1000 m^2)… convert that ratio ...1/1e06m^2 = ?/1m^2

Saskia_Martin · Answer

Thanks for the quick reply. It still doesn't really answer my question though. I tried to set the area units to square meters but the only thing that happens is, that the numbers are now lower (eg 0.000027).