What metric-dimension combination is not valid?
- Avg. Time on Page / Device Category
- Sessions / Bounce rate
- Sessions / Source
- Total Events / User Type
In Google Analytics, every website visitor has a corresponding source and medium. For example, google/organic, example.com/referral, and newsletter1/email. Source and Medium are default source dimensions in Google Analytics.
Tip: Don’t confuse sources with mediums as it often happens. Source is the origin of your traffic. While Medium is a category of a traffic source.
Learn more on the official Google support website.