Year-Over-Year Calculation Does Not Compare Corresponding Date Parts With Incomplete Years

Issue

When using the Year-over-Year Growth Quick Table Calculation on a series of years which are incomplete (ex. data for Q1, 2, and 3, but not Q4, etc.) the YoY% Growth calculation does not run on matching date parts.

Environment

Tableau Desktop

Resolution

The example below uses Quarters as the datepart.

On the Measure Values or Text shelf, right-click field with the table calculation, and select Edit in shelf.
In the formula, change both instances of -1 to -4, and then click OK.
Right-click the field again and select Edit table calculation.
For At the level, select Quarter of Date, and click OK.

Cause

Tableau Desktop runs table calculations based on the index of the values in the view, instead of their actual associated date parts. This way one year may begin with January (month 1, value 1), another year may only have data starting with March (month 3, value 1). Because they are both value 1 per the index, the YoY% Growth will be run between January and March.