Your question is Measure Real Impact Beyond Novelty. 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 consumer-facing campaign test where early results look positive, but the lift may fade once the novelty wears off. Your team wants to know whether the campaign created a real behavioral change or only a short-term spike.
How would you determine whether the campaign had a real impact or just a short-term novelty effect? Walk through how you would define success, analyze the result over time, and decide whether to ship.