A z-score refers to the number of standard deviations each data value is from the mean, with a z-score of zero indicating the exact mean. Z-scores are useful for analyzing numbers in the context of the rest of the field.
To learn more about z-scores, see What is a z-score? What is a p-value?.
Example
A GIS analyst for a nongovernmental organization is analyzing a disease outbreak. Calculate Z-Score can be used to determine the areas where the outbreak is concentrated.
Run Calculate Z-Score
Use the following steps to calculate a z-score:
- Create a map, chart, or table using the dataset with which you want to calculate the z-score.
- Click the Action button
. - Do one of the following:
- For chart and table cards, click How is it distributed in the Analytics pane.
- For a map card, click the Find answers tab and click How is it distributed.
- Click Calculate Z-Score.
- For Choose a layer, select the dataset to use to calculate the z-score.
- For Choose number field, choose the field to use to calculate the z-score.
The field must be a number or rate/ratio.
- Expand Additional options and provide values for Mean and Standard Deviation if necessary.
If no values are provided, the mean and standard deviation are automatically calculated.
- For Name the result field, provide a name for the new field.
- Click Run.
Usage notes
To access Calculate Z-Score, click the Action button under How is it distributed on the Find answers tab. The input layer can be a point, a line, or an area layer.
A number field must be specified as the field to calculate the z-score. The number field is used in the (number-average)/standard_deviation equation.
You can provide mean and standard deviation values. If you don't provide values, the mean and standard deviation is automatically calculated.
Calculate Z-Score adds a new number field to the input layer. The field name is automatically populated in the Calculate Z-Score pane, but you can change it before running the calculation.