In statistics, a **z-score **tells us how many standard deviations away a value lies from the mean.

We use the following formula to calculate a z-score:

**z = (x – μ) / σ**

where:

**x**is a single raw data value**μ**is the population mean**σ**is the population standard deviation

To calculate z-scores in Power BI, you can use the following syntax in DAX:

Z Score = VAR Xi = 'my_data'[Points] VAR MeanValue = AVERAGE('my_data'[Points]) VAR StDevValue = STDEV.P('my_data'[Points]) RETURN DIVIDE(Xi - MeanValue, StDevValue)

This particular formula will create a new column named **Z Score** that contains the z-score of each value from the **Points** column in the table named **my_data**.

The following example shows how to use this formula in practice.

**Example: How to Calculate Z-Scores in Power BI**

Suppose we have the following table named **my_data** in Power BI that contains information about points scored by basketball players on various teams:

Suppose that we would like to calculate the z-score for each value in the **Points** column.

To do so, click the **Table tools** tab and then click the **New column** icon:

Then type the following formula into the formula bar:

Z Score = VAR Xi = 'my_data'[Points] VAR MeanValue = AVERAGE('my_data'[Points]) VAR StDevValue = STDEV.P('my_data'[Points]) RETURN DIVIDE(Xi - MeanValue, StDevValue)

This will create a new column named **Z Score** that contains the z-score for the corresponding value in the **Points** column:

Here is how to interpret the values in the **Z Score** column:

- The first points value of 22 is
**0.1788**standard deviations**below**the mean points value. - The second points value of 14 is
**1.2005**standard deviations**below**the mean points value. - The third points value of 18 is
**0.6897**standard deviations**below**the mean points value. - The fourth points value of 39 is
**1.9924**standard deviations**above**the mean points value.

And so on.

**Related:** How to Interpret Z-Scores (With Examples)

**Additional Resources**

The following tutorials explain how to perform other common tasks in Power BI:

How to Calculate Average in Power BI

How to Calculate Standard Deviation in Power BI

How to Rank Values by Group in Power BI