In Custom Reports, what must metrics and dimensions share in order to report accurately?

• Same scope
• Same index
• Same Custom Report
• Same view

Correct answer is:

• Same scope

Explanation: Not every metric can be combined with every dimension. Each dimension and metric has a scope: user-level, session-level, or hit-level. In most cases, it only makes sense to combine dimensions and metrics that share the same scope.

Read more here: https://support.google.com/analytics/answer/1033861