Variables in DAX is a relatively new feature and is available in
- Power BI Desktop
- Excel 2016
- SSAS Tabular 2016
Variables are not available in Excel 2013 or Excel 2010.
Click through to see how to assign and use variables. It’s interesting to see how they’re local to a measure, so at this point at least, you can’t share variables between measures. Given what DAX is supposed to be, that’s probably the right choice.