Common Data Analyst interview questions covering SQL, statistics reasoning, and business communication.
Write a query to find duplicate records in a table.
Group by the columns that should be unique, then filter using HAVING COUNT(*) > 1 — this returns every combination of values that appears more than once, revealing the duplicates.
How would you explain a complex analysis to a non-technical stakeholder?
Lead with the conclusion, not the method — what does this mean for the business decision at hand. Use a simple visual rather than a table of numbers, and be ready to go deeper only if asked, rather than front-loading every technical detail.
What's the difference between INNER JOIN and LEFT JOIN?
INNER JOIN returns only rows with matches in both tables. LEFT JOIN returns all rows from the left table, with NULLs filled in for any that have no match in the right table — important when you need to see 'no data' as a signal, not just drop those rows silently.
How do you handle missing data in a dataset?
It depends on why it's missing and how much. Options include removing incomplete rows if the loss is small, imputing a reasonable value, or flagging missingness itself as a feature — but the decision should be based on understanding the cause, not a default habit.
Walk me through how you'd approach a new dataset you've never seen before.
Start with basic exploration — row count, column types, missing values, obvious outliers. Then look for the story: what questions could this data plausibly answer, and does the data actually support answering them reliably.
Go deeper
These questions are just the surface
Our Data Analyst Track program builds the hands-on experience behind these answers — not just memorized responses.
