None values

Cells without a formula, or formulas that lead to calculations such as a division by zero, evaluate to the none value. This is a special value in Causal, and can also be derived by using the none helper variable, or by adjusting the Empty Value setting of a variable to none.
None is special in that any mathematical operation it is part of also evaluates to none - for example, 1 + none = none.
The exception to this is in aggregations: when aggregating a category's items, none values are simply excluded from the computation. This is because it is useful to see aggregated values even if some underlying cells contain none values, as is typical in use-cases such as headcount modelling.
For example, if you're wanting to see the average bonus across your employees, but exclude from the average those employees who do not receive a bonus (and therefore are none), you would do the following to the Bonus by Employee variable:
🚨 Note that if you try to use that aggregated variable in another formula - it will be treated as none- see Troubleshooting for more.