IV. a. Using the Spatial Join Tool
             Estimated time:
             3 minutes
The spatial join combines attributes from multiple layers and adds them to one layer. In this case you will be finding the absolute average ozone contribution to the census tracts that are overlapped by the ozone values. Absolute average being that every ozone square that touches or lays within a census tract has 100% of its value added to that census tract, and then the total ozone value is divided by the number of ozone tracts that contribute. This is different from the area weighted average, which is a part of the more advanced path that can be taken to perform this module.
In this exercise, you will:
  • Use the spatial join tool


                                                   Start VideoDemo

Text Version:

    1. On the Standard Toolbar click the ArcToolbox tool (the red toolbox) click on Analysis Tools, then Overlay, and double click on Spatial Join

    2. Within the Spatial Join window under the Target Features drop down menu choose your Clipped Census layer, and under Join Features choose your Ozone layer

    3. Click Ok >> Close

    4. You now have a layer titled Census_Clip_SpatialJoin (or something very similar), this layer will look identical to the Clipped Census Tract layer, but will have the values of the Ozone layer added to the census tract layers. In the properties section of the tab switch to your hour, under Quantities (assigned by your professor/TA), and then to the EightHrAvg values and compare to the ozone layer, comparing your hour assigned and the eight hour average layer you just created.

    5. Turn off the Ozone layer now.
      Wanna bet if now would be a good time to save?!