Welcome to your interview.
The question is on your right: Diagnosing ROAS Drop. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
If a major programmatic campaign's return on ad spend (ROAS) dropped by 20% week-over-week, what steps would you take to diagnose the issue?