Question bank

Interview questions, with guidance on how to answer

834 questions across 64 roles. Open one to see what a strong answer includes and common slips, then drill it out loud with Ava. New to answer structure? Start with the learning hub.

572 questions match your filters.

TechnicalAny levelData Engineer
How do you deal with upstream application teams changing their database schema and breaking your pipelines?
Tests: Data quality & testing
TechnicalEntry levelData Scientist
How would you explain a p-value to a product manager who has never taken a statistics course?
Tests: Statistics & experimentation
TechnicalEntry levelData Scientist
You get a dataset where about a fifth of the values in an important column are missing. How do you decide what to do?
Tests: Data wrangling & SQL
TechnicalEntry levelData Scientist
What is overfitting, and how would you spot it in a model you just trained?
Tests: Predictive modelling
TechnicalMid levelData Scientist
Tell me about a split test or experiment you designed or analysed. How did you choose the success metric and the sample size?
Tests: Statistics & experimentation
TechnicalMid levelData Scientist
You're building a fraud model where only one in a thousand transactions is fraud. How would you evaluate whether it's any good?
Tests: Model evaluation
TechnicalMid levelData Scientist
A stakeholder asks you to build a churn model. What questions do you ask before writing any code?
Tests: Problem framing
TechnicalSeniorData Scientist
How do you decide between a simple interpretable model and a more complex one when the complex one is only slightly more accurate?
Tests: Predictive modelling
TechnicalAny levelData Scientist
How do you check that the data you're analysing actually means what you think it means?
Tests: Data wrangling & SQL
TechnicalAny levelData Scientist
After a model goes live, how would you know it's starting to get worse?
Tests: Model evaluation
TechnicalEntry levelData Analyst
What's the difference between an inner join and a left join, and when could picking the wrong one give you misleading numbers?
Tests: SQL querying
TechnicalEntry levelData Analyst
You're handed a spreadsheet of sales with duplicate rows, mixed date formats and some blank regions. How would you clean it up?
Tests: Data cleaning & spreadsheets
TechnicalEntry levelData Analyst
How do you decide which kind of chart to use for a particular piece of data?
Tests: Visualisation & dashboards
TechnicalMid levelData Analyst
Weekly sign-ups dropped fifteen percent last week. Walk me through how you'd figure out why.
Tests: Analytical problem solving
TechnicalMid levelData Analyst
If you were asked to define the key metrics for a subscription business, which would you choose and why?
Tests: Metrics & business sense
TechnicalMid levelData Analyst
Tell me about a complex query you wrote, maybe using window functions or several steps. What problem did it solve?
Tests: SQL querying
TechnicalSeniorData Analyst
A marketing manager says a campaign worked because sales went up the month it ran. How would you test whether that's really true?
Tests: Basic statistics
TechnicalAny levelData Analyst
How would you explain the difference between an average and a median to a colleague, and when does the median matter more?
Tests: Basic statistics
TechnicalEntry levelMachine Learning Engineer
Why do we split data into training, validation and test sets, and what goes wrong if information leaks between them?
Tests: Model training & evaluation
TechnicalEntry levelMachine Learning Engineer
How would you turn a notebook a data scientist gave you into code that's safe to run in production?
Tests: Software engineering practices