There are millions of possible answers to this question... Examples: - Conversion rate grouped by browser and browser version to find browser specific bugs. -

There are millions of possible answers to this question... Examples: - Conversion rate grouped by browser and browser version to find browser specific bugs. - Total revenue per user per marketing channel / search keyword / ... to optimize budget allocation. - Revenue by mobile OS version share to decide testing procedures to not optimize for users that don't contribute to your bottom line. - Client side loading times per user location and provider to optimize infrastructure placement. - ...