Data Analyst Interview Prep

1. Given an orders table with customer_id, order_id, order_date and amount, return each customer's first order date and the number of orders they placed in the following 30 days.
2. Write a query that returns the top three products by revenue in each category for the last full calendar month.
3. Monthly active users dropped in one region last month. Which tables would you query first, and what would you check before trusting the drop?

Strong answers state assumptions, such as time zones, refunds or duplicates, and explain how they would check the output, for example by reconciling totals with a known figure.

1. How would you define an active user for a budgeting app? What would make the definition misleading?
2. Conversion rose but revenue fell over the same week. Give three possible explanations and how you would test each.
3. A stakeholder wants one number to track customer satisfaction. What would you propose and what would you warn them about?

Interviewers look for definitions tied to the decision being made, awareness of trade-offs and a plan to validate.

A typical prompt: a subscription business wants to know why churn increased this quarter. Structure your answer: clarify the definition and time frame, segment by plan, tenure, channel and region, look for changes in product, pricing or support, then propose the analysis and what you would recommend depending on the findings.

Keep it practical. Saying what you would look at first, and why, matters more than listing every possible cut.

Lead with the answer in the first few lines. Use a small number of clear charts, explain assumptions and data issues, and suggest next steps. Many reviewers decide within the first page whether to read on.

Practise explaining a finding to a non-technical manager in three sentences: what happened, why it matters, what to do. Prepare one example of an analysis that changed a decision, and one where you were wrong and what you learned.