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?


1 Answer 1


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. enter image description here
  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): enter image description here

  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. enter image description here

  • Can you think of anyway to make a standard python script for this to be used in field calculator? I am not able to get the mean and SD values of a field using python in the calculator.
    – Salman
    Oct 20, 2016 at 12:40
  • Made it myself, was not that hard, here is link to the script: dropbox.com/s/fgx3e4l7pq02pd7/Zscore.py?dl=0
    – Salman
    Oct 20, 2016 at 14:04
  • Can I also have the script, please?
    – peter
    Aug 10, 2017 at 9:28
  • It would have been better to include that script as an answer
    – Shawn
    Dec 20, 2018 at 2:48

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