Matt Allington wants to solve a problem:
Using a switch measure to toggle results is a mature and common technique used in Power BI and Power Pivot for Excel. For example, a switch measure can be used to toggle what appears on a chart so that the end user can easily switch the data being visualised (see image below).
This technique uses a disconnected table, a slicer to receive the user selection, and a switch measure to change the result of the measure based on user input. When you select an option on the slicer you can have your chart update to show the result you want to see in the chart. I blogged about this in 2014 here.
The switch measure has a drawback, though: you can only have one number format, so Matt has a new solution using calculation groups.