Introduction to simple spatial statistic tools

The following tutorial takes crime data in a 2 mile radius from UCLA taken over a 3 month period (September to November 2012) and applies several statistical tools in ArcGIS.

Setup

  1. Add the tutorial data (crime.shp) in a new ArcMap project space.
  2. Add a base layer (recommended: “Light Gray Canvas”)
  3. Now symbolize the crime layer.  Right click on it, and go to properties, symbology tab.  Select “categories”, “unique values”.
  4. Under “Value field”, select “type”, and click on the “Add all values” button below.
  5. Change the symbology and colors to your liking

Find the central mean for each crime type

  1. Bring up the ArcToolbox panel (Geoprocessing, ArcToolbox), scroll down and expand “Spatial Statistics Tools”, “Measuring Geographic Distributions”
  2. Double click on “Mean Center”.  In the pop up window, choose “crime” for the input feature class, and “type” for the Case Field, and click “OK”.
  3. Wait a few seconds… until a new layer appears on your map called “crime_MeanCenter”.
  4. Symbolize the new layer.  Right click, properties, symbology tab, and choose “Categories”, “Unique values”.
  5. Under “Value field”, choose “type”, and click the “add all values” button below.
  6. Symbolize and color your new layer to your liking.
  7. Now let’s label these points.  Choose the “Labels” tab and check the box next to “Label features in this layer”.  Feel free to change the symbology of your labels as you please.
  8. Let’s allow labels to overlap.  Before you click “OK”, click on “Placement Properties”, and choose the “Conflict Detection” tab, and check the box for “Place overlapping labels” (below).  Then, click OK twice.
  9. Examine your map with the new points.  What do these points reveal?

Find the Directional Distribution of each crime type

  1. Bring up the ArcToolbox panel again, and double click on “Directional Distribution”, also located under “Spatial Statistics”, “Measuring Geographic Distributions”.
  2. Select “Crime” for input feature class, and “type” for case.
  3. Wait until you get a new layer called “Crime_DirectionalDistribution”.  Right click on the layer and go to properties, and go to the Symbology tab.  Expand Categories, and choose “Unique values”.
  4. Under “Value field”, choose “type”, and click on the “add all values”.
  5. Let’s also set a transparency to the ellipses.  Click on the “Display” tab and set the transparency to 50%.
  6. Examine the new map with ellipses.  What do these shapes reveal?

 

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