Data Analyst interview questions
5 questions asked in Data Analyst interviews, from job seekers and our own interviews, each read by us before publishing.
Technical or skills round
What's the difference between a LEFT JOIN and an INNER JOIN, and when has it mattered?
Tip: Explain the difference, then give a real case where the wrong join silently dropped or duplicated rows and how you caught it.
How do you deal with missing or messy data?
Tip: Explain how you first find out why it is missing, then choose to drop, fill or flag it, and how you document the choice so the result can be trusted.
Write a SQL query to find the top 3 products by revenue in each month.
Tip: Use a window function: ROW_NUMBER() or RANK() OVER (PARTITION BY month ORDER BY revenue DESC), then filter to rank 3 or less. Mention how you would handle ties.
Hiring manager
Tell me about a dashboard you built. Who used it and what changed?
Tip: Name the users and the decision they made with it. Mention what you removed to keep it simple.
Assessment or case study
Here is a dataset. What would you look at first?
Tip: Check shape, data types, missing values and duplicates; then the key metric over time and by segment. Say which question from the business you would be trying to answer.