KNOWLEDGE BASE

Null or Missing Data Produces Incorrect Average


Published: 07 Jun 2016
Last Modified Date: 04 Jun 2018

Issue

When averaging a field, then the result does not include NULL or missing data

Environment

Tableau Desktop

Resolution

For NULL data, wrap the field in ZN(). For example, the following calculation:
AVG( [Sales] )

Could become:
AVG( ZN( [Sales] ))
 
For missing data it may not always be possible to replace missing values with zeros. Depending on how the view is built it may be possible to achieve the desired results with table calculations. For directions, please see Populate Empty Cells in a Text Table with Zeroes or Existing Data

Cause

Aggregations ignore NULL values. The function ZN() converts NULL values into zeros in order to be included in the average.

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