Check the data pipeline before investigating the business. Many "metric drops" are actually incomplete data loads or tracking issues.
Strong answers follow a systematic process: verify the data pipeline first (is the data complete? recent deploys? source changes?), then segment the drop (by region, channel, device, cohort), check for external factors (seasonality, holidays, competitor actions), and communicate findings with appropriate caveats.
Practical analytical skill. Red flag: jumping to business conclusions without checking data quality first. Good sign: systematic elimination of data issues before investigating business causes.