You work on a ride-sharing marketplace and want to test a new ad experience in the rider app, such as sponsored placements in the Lyft app. The team believes the change will increase ad engagement, but you want to validate that lift without harming the core rider experience.
How would you validate the hypothesis that this ad change improves user engagement with ads? Walk through how you would design the A/B test, choose metrics, and decide whether the result is strong enough to ship.