Intermediate everything in Analytics & Metrics, page 10
Design a Data Quality Monitoring & Alerting System
This tests translating business needs into a concrete data validation strategy. A good answer defines checks based on business impact (freshness, volume, schema), then outlines a tiered alerting system. A red flag is naming tools before defining the problem.
Design a Centralized Metrics Layer
This tests your grasp of data governance and creating a single source of truth. A good answer defines a semantic layer between the data warehouse and BI tools, centralizing metric definitions in code.
Design a data warehouse model for tracking feature adoption
This tests your grasp of data warehousing star schemas for efficient behavioral analysis. A strong answer proposes a central events fact table linked to users, features, and time dimension tables.
Explain cohort analysis for user retention and write a pseudo-query
Tests your ability to use precise metrics. A good answer defines a cohort, explains why it isolates variables better than aggregate data, outlines the calculation, and provides a clear pseudo-query.
Explain event schemas and the purpose of a schema registry
This tests your grasp of data governance in event-driven systems. A good answer defines a schema as a contract, a registry as the enforcer, and then details specific downstream failures like broken pipelines and bad analytics. A red flag is being too vague.
How would you design a data model for a feature adoption dashboard?
Tests applying dimensional modeling to a business need. A good answer defines a central fact table (e.g., feature_usage) and related dimensions (user, feature, date). A red flag is designing a transactional model or being too vague about the schema.
Describe dbt's role in a modern analytics stack
Tests your grasp of the ELT paradigm and applying software engineering principles to data. A good answer defines dbt as the 'T' in ELT, contrasts its in-warehouse SQL approach with traditional ETL, and clarifies its relationship with orchestrators like…
How would you measure P95 latency by geographic region?
Tests your ability to design a practical metrics pipeline, considering instrumentation, data types (metrics vs. logs), and aggregation. Instrument the API with a histogram metric and a region label, then query using histogram_quantile.
Forecasting inventory with trend and weekly seasonality?
This tests mapping a business problem to a statistical tool. A good answer names Holt-Winters, explains its level, trend, and seasonal components, and discusses additive vs. multiplicative seasonality.
Train-test split vs. time-series cross-validation?
Tests if you see why temporal data breaks random splits. Contrast random sampling with sequential 'walk-forward' validation, where you only use past data to predict the future.
Explain stationarity in a time series
This tests your grasp of core time series modeling assumptions. A strong answer defines stationarity (constant mean/variance), explains its importance for ARIMA (stable patterns), and names a test (ADF) and a fix (differencing).
Primary vs. Guardrail Metrics in Experiments
This tests if you can balance improving a key metric with not harming the user experience. Define primary (the goal) and guardrail (don't harm) metrics. Give an example where a guardrail regression (e.g., latency) blocks a feature ship.
Handling the novelty effect in experimentation
This tests your grasp of second-order effects in A/B testing. A great answer defines the novelty effect, explains how it inflates initial metrics, and suggests mitigating it by running tests longer or segmenting by user tenure. A red flag is ignoring it.
Why is stopping an A/B test when it hits significance problematic?
Tests your understanding of the 'peeking problem' in A/B testing. A great answer defines peeking, explains how it inflates the Type I error rate (false positives), and states the need for a predetermined sample size.
How do you determine A/B test sample size and duration?
This tests your ability to connect business goals to statistical parameters. A good answer defines the four power analysis inputs (baseline, MDE, alpha, power) and explains trade-offs, then converts sample size to duration using business cycles.
Explain Simpson's Paradox with a user engagement example
This tests your understanding of statistical pitfalls in A/B testing. A good answer defines the paradox, gives an example where a feature fails in aggregate but wins in every segment, and attributes it to a confounding variable.
How to Statistically Test a 10% DAU Drop?
Tests your knowledge of hypothesis testing. A good answer outlines the steps: state a null hypothesis, choose a test (e.g., Z-test), calculate a p-value, and compare it to a significance level (alpha).
Explain the difference between correlation and causation
Tests if you can avoid statistical fallacies. First, define correlation (association) and causation (cause-effect). Then, explain the difference via a confounding variable. A red flag is giving an example where one metric actually could cause the other.
p-value is 0.08, significance is 0.05. Ship it?
This tests your ability to translate statistical risk for business partners. Explain that p=0.08 means an 8% chance of a false positive, quantify the cost of a bad decision, and suggest extending the test to increase power.
An A/B test has imbalanced traffic. What do you do?
This tests your ability to spot confounding variables and Simpson's Paradox. A good answer first invalidates the aggregate result, then proposes segmenting by device to salvage insights, and finally investigates the root cause.
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