Your question is Incrementality Test for Campaign Sales. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You work on a retail analytics team evaluating a campaign that ran across a customer audience and appears to have boosted sales. Leadership wants to know whether the campaign created new demand or simply pulled forward purchases that would have happened anyway.
How would you analyze whether the campaign drove incremental sales or just shifted existing demand? Explain how you would structure the experiment or readout, define success, and decide whether the campaign should ship.