Your question is Diagnose Cross Campaign CTR Drop. 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 are reviewing performance across several digital advertising campaigns and notice that click-through rate dropped 15% week over week, from 1.20% to 1.02%, across multiple active campaigns in StackAdapt. Spend, impression volume, and campaign count are roughly flat, and the decline appears across more than one advertiser and inventory source. There were recent creative refreshes and budget adjustments, but no obvious single campaign failure.
If you notice a sudden 15% drop in click-through rate (CTR) across multiple campaigns, what steps would you take to investigate the root cause?