Have you ever seen the error: “Cannot mix aggregate and non-aggregate arguments in this function?” If you’ve worked with Tableau for any period of time, you probably have! You could have seen this in an IF statement, a CASE statement, or just a regular calculation!

The big idea is that we can’t aggregate part of our calculated field while not aggregating another part of the same calculated field.

This is because aggregated functions run at a "summary" level, while a non-aggregated function runs at a “row by row” level. So, when we try to use these in one function, Tableau gets confused at exactly how to execute what we’re asking!