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Visualize two continuous and one categorical variable?
Tests your ability to map data to visual encodings. A great answer starts with a scatter plot, then adds the categorical data using color, shape, or faceting, explaining the tradeoffs. A red flag is suggesting a 3D chart, which is difficult to read.
How would you visualize three years of monthly revenue?
This tests your grasp of time-series visualization and data integrity. A strong answer picks a line chart, insists on a zero-based Y-axis and clear labels, and adds context like seasonality.
Define idempotency in data processing and give an example
Tests your grasp of distributed systems reliability. Define idempotency (N>1 runs = 1 run), explain its role in fault-tolerant retries, and provide a concrete example using transaction IDs. A red flag is confusing it with immutability.
How do you shift analytics from growth to profitability?
This tests your ability to translate business strategy into technical changes. A great answer connects profitability drivers to specific updates in event taxonomy, data models, and dashboards. A red flag is ignoring core financial metrics like LTV and CAC.
How would you define and calculate Weekly Active Users (WAU)?
This tests your product sense and technical precision in defining a core business metric. A great answer defines 'active' with specific user actions, outlines the SQL/event-based calculation, and discusses pitfalls like bots and background events.
When is A/B testing not feasible, and what is an alternative?
Tests your grasp of causal inference when randomization isn't possible. A great answer names a scenario (like a regional launch), proposes Difference-in-Differences (DiD), and explains its core 'parallel trends' assumption.
Calculate Sample Size for a 2% A/B Test Lift
This tests if you connect statistical inputs to business goals. A good answer defines baseline rate, minimum detectable effect (MDE), and power, then explains MDE as a cost/benefit trade-off.
Design a Schema Validation System for Analytics Events
This tests your ability to balance data quality, performance, and developer experience. A good answer defines a central 'Tracking Plan,' enforces it on the client for feedback and the server for integrity, and quarantines failed events.
Calculate MRR from a subscriptions table using SQL
Tests your ability to translate a business metric (MRR) into a precise SQL query. A great answer filters for active subscriptions this month and sums their prices, correctly amortizing annual plans.
What does a p-value of 0.03 mean in an A/B test?
This tests your practical grasp of statistical significance. A good answer defines p-value (probability of the result if the null hypothesis is true), explains that p=0.03 is significant vs. alpha=0.05, and concludes you can reject the null.
How do you handle timezones for a daily global sales report?
This tests your understanding of time data modeling and business requirements. A good answer stores events in UTC with a timezone identifier, then converts to the business's chosen 'day' at query time. A red flag is storing local time without context.
How would you implement Change Data Capture (CDC)?
Tests your grasp of data replication trade-offs. A great answer compares log-based CDC (low impact, complete) with query-based methods (higher impact, misses deletes), and recommends log-based CDC for its minimal production impact.
Propose a multi-touch attribution model and its data pipeline
Tests your grasp of attribution models and their data engineering needs. Propose a rule-based model (e.g., time-decay), outline the data pipeline for it, and acknowledge privacy-driven signal loss. A red flag is ignoring the challenge of identity resolution.
Transform a time series for a supervised learning model?
This tests your ability to reframe a time series problem for tabular models. A great answer explains creating features from lags, rolling windows, and calendar data, then emphasizes using a time-aware validation split. A red flag is forgetting validation.
Find leading indicators for long-term churn
This tests your ability to translate a business problem into a data investigation. A strong answer defines churned vs. retained cohorts, hypothesizes key early behaviors, and compares their frequency to find a leading indicator.
Calculate Daily Active Users (DAU) with SQL
This tests product sense and SQL fundamentals. Define 'active' with a core product action, describe the event data needed, then write a COUNT(DISTINCT user_id) query. A red flag is writing SQL before defining the business logic for 'active'.
Client-Side vs. Server-Side Event Tracking
Tests your grasp of data integrity and architectural trade-offs. A great answer defines both, favors server-side for reliability (avoids ad-blockers), but notes client-side's richness for UI events. A red flag is presenting them as equal choices.
How would you build a SQL query for a conversion funnel?
Tests your ability to translate a business need into a technical SQL solution. A good answer uses CTEs or LEFT JOINs to model sequential steps, counts users at each stage, and discusses attribution.
Trade-offs: Bundled vs. Warehouse-Native Product Analytics
This tests your grasp of modern data stack architecture. A great answer weighs trade-offs in data control, cost, query flexibility, and team capabilities. A red flag is ignoring total cost of ownership and engineering overhead for a warehouse-native setup.
Why don't analytics and backend user counts match?
This tests your systematic debugging and understanding that 'user' has different definitions. A good answer first defines 'user' in each system, then investigates tracking implementation, timing differences, and filtering.