Yahoo·Data Scientist·Technical Phone Screen
- Yahoo Mail's DAU dropped 10% compared to the prior 7-day baseline. You're the on-call analyst. Walk through your full investigation: how do you verify the drop is real, isolate the cause using a metric tree and segmentation, run SQL or Python checks to find the top contributing segments, design a causal test to validate your hypothesis, and then recommend mitigations and a monitoring plan with rollback criteria. What do you do in the first two hours?
“This was a lot.”