Data Investigation and Root Cause Analysis Questions

Techniques and a structured process for diagnosing an unexpected change in a metric, dataset, or system signal using quantitative evidence complemented by qualitative signals. Candidates should demonstrate how to validate that an observed change is a real signal and not noise, or a reporting, instrumentation, or pipeline problem, by checking data quality, event or record counts, sampling, schema stability, and pipeline or data-flow integrity. Describe slicing and decomposition strategies such as cohort or population segmentation, geography and platform segmentation, feature-level analysis, time series decomposition to separate trend and seasonality, funnel and velocity analysis, retention analysis, and variance analysis. Explain how to form, prioritize, and test hypotheses; design diagnostic queries and tests using structured query language or equivalent tooling; and correlate the change with plausible triggers such as releases or deployments, configuration or schema changes, experiments, campaigns, upstream system incidents, or external events. Include how to combine quantitative findings with qualitative evidence such as interviews, logs, session or trace replay, support tickets, or incident timelines to strengthen causal inference. Finally, cover communicating concise findings and actionable recommendations to stakeholders, creating reproducible queries and monitoring dashboards, alerts, or runbooks, and mentoring others on a systematic investigation approach. This applies broadly to investigating anomalies in business metrics, product data, system or service health signals, financial figures, or model performance, not only one of these domains.