Hi all,

I am running a Kernal Density analysis on a point layer (sewage overflow locations). The coordinate system I am using is CA State Plane NAD 83

Point features: OverflowLocs

Population field: NONE (this means by default that each point will be counted once)

Output Raster: OverflowDens

Output cell size: 50 (feet)

Search radius 880 (feet) = 1/6 mile which suits my needs for neighborhood/block level data

Area units: Square Miles

Using these parameters, my result looks great, but I don't understand the units of the output values:

lowest (coolest) value range: 0 - 6.6259

highest (hottest) value range 205.4043 - 336.5979

The ArcGIS Help describes the output as "magnitude per unit area". To me, this means that the highest value then reads as 336.5979/1sq mi. This is considering that my input Area Units were Square Miles, so I'm assuming that my "unit area" is 1 square mile. Correct?

Further, what are the units (or at least a generic definition) for "magnitude" in this case? Is it the density of the points (ie. points per sq mile? Or is it points per search radius (880 feet), or some other units?

Thanks for your help,

Christi

I am running a Kernal Density analysis on a point layer (sewage overflow locations). The coordinate system I am using is CA State Plane NAD 83

**FEET**. My inputs include:Point features: OverflowLocs

Population field: NONE (this means by default that each point will be counted once)

Output Raster: OverflowDens

Output cell size: 50 (feet)

Search radius 880 (feet) = 1/6 mile which suits my needs for neighborhood/block level data

Area units: Square Miles

Using these parameters, my result looks great, but I don't understand the units of the output values:

lowest (coolest) value range: 0 - 6.6259

highest (hottest) value range 205.4043 - 336.5979

The ArcGIS Help describes the output as "magnitude per unit area". To me, this means that the highest value then reads as 336.5979/1sq mi. This is considering that my input Area Units were Square Miles, so I'm assuming that my "unit area" is 1 square mile. Correct?

Further, what are the units (or at least a generic definition) for "magnitude" in this case? Is it the density of the points (ie. points per sq mile? Or is it points per search radius (880 feet), or some other units?

Thanks for your help,

Christi

How should I intrepret the output of density tools?

In particular, you may be interested in converting density into expected count.

Best,

Eric