I want to create a calculated metric and I see the option compute separately. What does compute separately mean?
When you add a calculated metric to your query, the calculation may skew the results of other existing metrics and attributes in your query. Compute separately, when checked, runs its own calculations for the calculated metric.
Use this when your formula for the calculated metrics includes existing metrics or attributes.
For more information about creating calculated metrics and attributes, see the article: Creating standard calculated metrics and attributes.