Deriving Z-score values for given field using ArcGIS for Desktop?

I have a shapefile with an attribute field with a range of numerical values.

How do I derive z-score values for this field using ArcGIS for Desktop?

Answer

Here are the steps for calculating Z-Scores in ArcGIS, in this case I have included some screen captures of calculating Z-scores for a field named SourceData.

1. Open up the attribute table and right click on the field header for SourceData and select Statistics from the pop up menu.



2. Record the values for Mean and Standard Deviation. In this case the Mean is 565.43 and the Standard Deviation is 1954.39.


3. Create a new field to store the Z-scores, make sure that this field is a Double.


4. Right click on the field header of the new field you created in step 3.


5. 
   

   The formula for Z-Scores is SourceData - Mean / Standard Deviation. Here's what it looks like the Formula Calculator (Note the parenthesis around the first part of the formula):

   
   


6. 
   

   You can check your results by running Statistics on the zscore field. A Z-score will have a mean of zero and a standard deviation of one.