Interview questions
Interview questions to practise
Typical questions from graduate interviews, each with what it’s really asking, how to structure a strong answer and an example outline to adapt. When you’re ready, practise them out loud and get written feedback.
By role
Questions for
Questions for data analyst and data engineer interviews, and for data jobs in product teams, finance, health and retail, grouped the way interviews use them, with coding challenges to match.
- Data analyst interview questionsData analyst interviews
- Data engineer interview questionsData engineer interviews
- Product analyst interview questionsProduct analyst interviews
- Finance data analyst interview questionsBanking, insurance and fintech
- Healthcare data analyst interview questionsNHS and healthcare
- Retail data analyst interview questionsRetail and e-commerce
Question types
Know the type,
Most interview questions fall into a handful of types. Each type is testing something different, so each has its own best structure. Start with the guide to the type, then choose a question to work on.
- 7 questions
Background questions
“Tell me about yourself” and the story of your path so far.
- 48 questions
Competency questions
“Tell me about a time…” questions about what you’ve done.
- 22 questions
Strengths questions
What you enjoy, what comes naturally and what drains you.
- 24 questions
Motivation questions
Why this role, why this employer and why you.
- 11 questions
Values questions
How you act on your values: honesty, feedback and fairness.
- 18 questions
Situational questions
“What would you do if…” scenarios from the job.
- 81 questions
Technical questions
Knowledge the job needs, explained out loud, from data and software to finance.
- 8 questions
Brainteaser and estimation questions
“How many…?” questions you can’t look up.
- 25 questions
Case study questions
A business problem to work through out loud.
- 8 questions
Design questions
Design tables or a data pipeline out loud, from a short brief.
- 10 questions
Presentation questions
Prepare from a written brief, then present a recommendation.
Coding challenges
A technical round?
Data analyst and data engineer interviews often include a live SQL or Python task. Our coding challenges are original questions with realistic data: write your answer, run it in your browser and check it against hidden tests. Then practise explaining it out loud here.
Every question
All 262
Every question here is in our practice bank. Each page explains what the question is really asking, how to structure your answer and an example outline, with the time you’d have to answer it.
Background questions
- Tell me about yourself and what has brought you to apply for this role.2 minutes to answer
- What did you learn on a placement, internship or part-time job that your degree couldn’t have taught you, and how would you use it here?2 minutes to answer
- What from your current or last job will carry straight across into a data role, and what will you have to learn from scratch?2 minutes to answer
- Walk me through your CV, and tell me which experience on it you’d most like me to ask about.2 minutes to answer
- Why did you choose your degree, and how has it shaped what you want to do next?1 minute 30 seconds to answer
- What have you been doing since you finished your studies, and what has it given you?1 minute 30 seconds to answer
- Tell me about your dissertation or final-year project so that someone outside your subject would understand why it matters.2 minutes to answer
Competency questions
- Tell me about a time you worked in a team to reach a difficult goal. What was your role, and what was the outcome?Teamwork · 2 minutes to answer
- Describe a problem you solved where the answer wasn’t obvious. How did you work out what to do?Problem solving · 2 minutes to answer
- Tell me about a time something went wrong or you had a setback. How did you respond, and what did you learn?Resilience · 2 minutes to answer
- Give an example of when you spotted something that could be done better and acted on it without being asked.Initiative · 2 minutes to answer
- Tell me about a time you led other people, formally or informally. How did you get the best from them?Leadership · 2 minutes to answer
- Describe a time you had to explain something complicated to someone without your background. How did you make sure they understood?Communication · 2 minutes to answer
- Tell me about a time you had several deadlines at once. How did you decide what to do first?Organisation · 2 minutes to answer
- Describe a time your plans changed at short notice. What did you do?Adaptability · 2 minutes to answer
- Tell me about a time you caught a mistake that others had missed. How did you find it, and what happened next?Attention to detail · 2 minutes to answer
- Give an example of when you persuaded someone to change their mind. How did you approach it?Influencing · 2 minutes to answer
- Tell me about a time you went out of your way to help a customer, client or member of the public.Customer focus · 2 minutes to answer
- Describe a time you had to learn something new quickly. How did you go about it?Learning · 2 minutes to answer
- Tell me about a time you looked beyond your own task to understand the bigger picture. How did that change what you did?Seeing the big picture · 2 minutes to answer
- Tell me about a time you helped introduce a new way of doing things. How did you bring other people along with the change?Initiative · 2 minutes to answer
- Tell me about a time you had to make a decision without all the information you wanted. How did you decide?Decision making · 2 minutes to answer
- Tell me about a time you had to give people a message they didn’t want to hear. How did you get it across?Communication · 2 minutes to answer
- Tell me about a time you worked with people outside your own team or organisation to get something done. How did you build the relationship?Teamwork · 2 minutes to answer
- Tell me about a time you helped someone else improve at something. How did you go about it, and what did you learn yourself?Leadership · 2 minutes to answer
- Tell me about a time you improved the service people received while working within fixed rules or resources.Customer focus · 2 minutes to answer
- Tell me about a time you had to deliver something important quickly without letting the quality slip. How did you manage it?Organisation · 2 minutes to answer
- Tell me about a time you noticed a way for an organisation to save money or earn more. What did you do about it?Commercial awareness · 2 minutes to answer
- Tell me about a time you had to perform well under intense pressure. How did you keep your focus?Resilience · 2 minutes to answer
- Tell me about a time you disagreed with a teammate about how to build or fix something. How did you resolve it?Teamwork · 2 minutes to answer
- Tell me about a time you worked with people from other disciplines on a technical project. How did you make sure the pieces fitted together?Teamwork · 2 minutes to answer
- Tell me about a time you used figures or records to improve something in a customer-facing job, such as in a shop, café or bar.Commercial awareness · 2 minutes to answer
- Tell me about a time you replaced a manual task, such as a spreadsheet updated by hand, with a query or a script. How did you make sure the new version was right?Initiative · 2 minutes to answer
- Tell me about a time you told someone you weren’t confident in a result they wanted to use straight away. What happened?Integrity · 2 minutes to answer
- Tell me about a time you turned down, or reshaped, a request for analysis. What did you offer instead?Judgement · 2 minutes to answer
- Tell me about a time you had to decide whether to use a piece of personal data at all, not just how to keep it safe.Integrity · 2 minutes to answer
- Tell me about a time something you built broke after it went live. How did you find out, and what did you change afterwards?Resilience · 2 minutes to answer
- Tell me about a time you chose between a quick fix and a proper one. Would you make the same choice again?Decision making · 2 minutes to answer
- Describe a time you explained a technical limit to someone who just wanted the data sooner. How did you handle it?Communication · 2 minutes to answer
- Tell me about a time you inherited code or a spreadsheet that nobody understood. How did you make sense of it?Problem solving · 2 minutes to answer
- Tell me about a time your analysis changed what someone decided to do. How did you make the case?Influencing · 2 minutes to answer
- Tell me about a time you joined a team or a place that worked very differently from what you were used to. How did you adjust, and what took you longest?Adaptability · 2 minutes to answer
- Tell me about something you organised from start to finish that had a lot of moving parts. How did you keep track of it all, and what nearly slipped?Organisation · 2 minutes to answer
- Tell me about a time a problem for a customer or client took days or weeks to put right. How did you keep them informed and keep their trust while it was sorted out?Customer focus · 2 minutes to answer
- Tell me about a time you disagreed with a decision made by someone more senior, such as a manager, lecturer or coach, and tried to change it. How did you go about it, and what happened?Influencing · 2 minutes to answer
- Tell me about something you’ve taught yourself outside your course or job. Why did you start, how did you keep going, and how do you know you’ve improved?Learning · 2 minutes to answer
- Tell me about a decision you made that affected other people and wasn’t popular with all of them. How did you reach it, and how did you explain it?Decision making · 2 minutes to answer
- Tell me about a time you saw that a change coming up, such as a new rule, a new system or a shift in what people wanted, would affect your work. What did you do to get ready?Seeing the big picture · 2 minutes to answer
- Tell me about a time something you were part of, such as a society, an event or a shop, had to compete for people’s time or money. What did you do to make it the one they chose?Commercial awareness · 2 minutes to answer
- Tell me about a period of several weeks when the pressure didn’t let up. How did you keep going, and how did you look after yourself and the quality of your work?Resilience · 2 minutes to answer
- Tell me about a time you had to follow a detailed procedure or set of rules exactly, where a small slip would have mattered. How did you make sure nothing was missed?Attention to detail · 2 minutes to answer
- An apprenticeship means studying for a degree alongside a job. Tell me about a time you balanced study with another big commitment over several months. How did you make it work week to week?Organisation · 2 minutes to answer
- Many internships end with a presentation to senior staff. Tell me about a time you presented your own work to people more senior or more expert than you. How did you prepare, and how did you handle their questions?Communication · 2 minutes to answer
- Tell me about a time you used data, a spreadsheet or reports in a job that wasn’t a data job, to change how something was done.Initiative · 2 minutes to answer
- How have you learned the skills for this role alongside work or other commitments? Tell me about a point where it got hard and what kept you going.Learning · 2 minutes to answer
Strengths questions
- What kinds of tasks give you energy, and why?1 minute 30 seconds to answer
- Describe a really good day at university or work. What made it good?1 minute 30 seconds to answer
- What achievement are you proudest of, and what does it say about you?1 minute 30 seconds to answer
- How would your friends or colleagues describe you, and would you agree?1 minute 30 seconds to answer
- What do you find you pick up faster than other people?1 minute 30 seconds to answer
- What kind of work do you find draining, and how do you handle it?1 minute 30 seconds to answer
- What do you enjoy doing in your own time, and what do you get out of it?1 minute 30 seconds to answer
- What’s something you’re working on getting better at, and what are you doing about it?1 minute 30 seconds to answer
- Do you get more satisfaction from starting things or from finishing them? Why?1 minute 30 seconds to answer
- Are you more of a detail person or a big-picture person? How do you know?1 minute 30 seconds to answer
- When you’re given a routine task, do you tend to stick to the way you were shown or look for a better way? Give me a recent example.1 minute 30 seconds to answer
- How do you like to be given feedback, and what’s the most useful feedback you’ve had so far?1 minute 30 seconds to answer
- Do you do your best work on your own or with other people? What have you noticed about yourself that makes you say that?1 minute 30 seconds to answer
- What kinds of patterns do you find yourself noticing, in numbers, in people or in how things work? Tell me about one you spotted.1 minute 30 seconds to answer
- When a group has nobody in charge, what role do you usually end up taking, and why?1 minute 30 seconds to answer
- How do you decide when to keep working something out on your own and when to ask for help?1 minute 30 seconds to answer
- Do you prefer to plan your work in detail, or to adapt as you go? What does that look like on a busy day?1 minute 30 seconds to answer
- How do you feel about working within rules and processes you didn’t design and can’t change?1 minute 30 seconds to answer
- Do you enjoy explaining things to people who see them differently from you? What makes it go well or badly?1 minute 30 seconds to answer
- How do you react when work you’ve put a lot into is changed or dropped because priorities have moved?1 minute 30 seconds to answer
- What’s something you’ve found yourself improving, even though nobody asked you to?1 minute 30 seconds to answer
- Think about the people your work would serve. Which part of serving them would give you the most satisfaction, and why?1 minute 30 seconds to answer
Motivation questions
- Why do you want this role, and what do you think it will involve day to day?2 minutes to answer
- Why do you want to work for us rather than one of our competitors?2 minutes to answer
- Where would you like your career to be in five years, and how does this role help you get there?1 minute 30 seconds to answer
- What would you bring to this team that other graduates might not?1 minute 30 seconds to answer
- Why do you want a career in public service, and what difference do you hope to make?2 minutes to answer
- What draws you to professional services, and why have you chosen this area of it over the others?2 minutes to answer
- Why do you want to be a commercial solicitor, and what have you done to test that interest?2 minutes to answer
- Why do you want to work in finance, and why this area of it in particular?2 minutes to answer
- What draws you to a career in technology, and what kind of problems do you want to work on?1 minute 30 seconds to answer
- Why do you want to work in the NHS, and which of its values means most to you?2 minutes to answer
- Why did you choose engineering, and what kind of engineering work do you want to do?1 minute 30 seconds to answer
- Why do you want to work in data? What first got you interested, and what have you done since to find out whether the work suits you?2 minutes to answer
- What would you most want to learn in your first year as an analyst, and how would you go about learning it?1 minute 30 seconds to answer
- Plenty of sectors could use the skills you have. Why this one rather than its closest neighbour?2 minutes to answer
- How does this organisation make or get its money, and what does it spend most of it on? Where would your role fit into that?2 minutes to answer
- What kind of manager gets the best out of you, and how would you work with one who manages differently?1 minute 30 seconds to answer
- If you joined us, what would you want to have done by the end of your first 90 days, and how would you go about it?2 minutes to answer
- What else are you applying for, and how does this role compare?1 minute 30 seconds to answer
- Why have you chosen a degree apprenticeship rather than going to university full time, and what do you think you’ll find hardest about it?2 minutes to answer
- What would you most want to learn during a placement year, and how would you use it when you go back for your final year?1 minute 30 seconds to answer
- You’ve built a career in another field. Why move into data now, and what makes you sure it’s the right move rather than a passing interest?2 minutes to answer
- This is a junior role, and your manager may be younger than you or newer to work. How do you feel about starting again at this level?1 minute 30 seconds to answer
- What will you miss about your current career, and what would you do if your first year in data turned out harder than you expect?1 minute 30 seconds to answer
- What do you know about what we do, and how did you find it out?1 minute 30 seconds to answer
Values questions
- Tell me about a time you did the right thing when it would have been easier not to.2 minutes to answer
- Tell me about some difficult feedback you received. How did you respond?2 minutes to answer
- How have you made sure everyone in a group felt included and able to contribute?2 minutes to answer
- Tell me about a time you were trusted with confidential information. How did you make sure it stayed confidential?2 minutes to answer
- Working together for patients is one of the NHS values. Tell me about a time you worked with others to put the needs of the people you served first.2 minutes to answer
- Respect and dignity is one of the NHS values. Tell me about a time you had to be honest with someone about what you could and couldn’t do for them.2 minutes to answer
- Commitment to quality of care is one of the NHS values. Tell me about a time you spoke up because something wasn’t good enough.2 minutes to answer
- Compassion is one of the NHS values. Tell me about a time you noticed someone was struggling and did something to help.2 minutes to answer
- Improving lives is one of the NHS values. Tell me about a small change you made that improved someone’s experience.2 minutes to answer
- Everyone counts is one of the NHS values. Tell me about a time you made sure someone who could have been left out got the same chance as others.2 minutes to answer
- Tell me about a time a rule or a way of doing things at work or university clashed with what you thought was right. How did you handle it?2 minutes to answer
Situational questions
- Your manager needs a report by 5pm, but the data you depend on won’t arrive until 4pm. What do you do?1 minute 30 seconds to answer
- A client emails you directly, unhappy that some work is late, while your manager is on leave. What do you do?1 minute 30 seconds to answer
- You’re checking a contract that must go to the client at 6pm. At 5pm you notice two clauses contradict each other, and the partner is in a meeting. What do you do?1 minute 30 seconds to answer
- A client phones wanting a quick answer to a legal question you’re not sure about, and your supervisor is out for the day. What do you do?1 minute 30 seconds to answer
- You realise a spreadsheet your team sent to a client yesterday contains an error you made. What do you do?1 minute 30 seconds to answer
- You’re working on a hospital reception desk when a patient’s relative becomes angry about a long wait. What do you do?1 minute 30 seconds to answer
- On a site visit, you see a contractor working in a way you think is unsafe, and you’re the most junior person there. What do you do?1 minute 30 seconds to answer
- An A/B test of a new feature showed no clear difference. The product manager asks you to split the results by age, device and region until you find a group where it won. What do you do?1 minute 30 seconds to answer
- Six months ago you built a dashboard for the sales team, and the usage figures show hardly anyone opens it. What do you do?1 minute 30 seconds to answer
- You’re going on three weeks’ leave tomorrow, and a colleague will run your weekly report while you’re away. How do you hand it over?1 minute 30 seconds to answer
- You notice that a colleague who has been in the team much longer than you skips a check the team’s procedure requires, to save time. Nothing has gone wrong so far. What do you do?1 minute 30 seconds to answer
- Two managers you work for each give you an urgent task for the same afternoon, and each says theirs must come first. What do you do?1 minute 30 seconds to answer
- A long-standing client asks you to waive a fee that only your manager can approve, and says they’ll move their business elsewhere unless you agree during the call. What do you do?1 minute 30 seconds to answer
- The morning after you send your team’s weekly report to thirty people, you notice that one of the figures in it is wrong. It doesn’t change the main message, and nobody has mentioned it. What do you do?1 minute 30 seconds to answer
- You’re one of four graduates preparing a presentation for senior managers on Friday. It’s Tuesday, and one of the four hasn’t started their section and has stopped replying to messages. What do you do?1 minute 30 seconds to answer
- A colleague from another team messages you asking for a customer’s contact details from a system you can use. They say it’s urgent and their own access hasn’t come through yet. What do you do?1 minute 30 seconds to answer
- In the second week of your internship, you finish the task you were given two days early. Your supervisor is in meetings all week. What do you do?1 minute 30 seconds to answer
- Two weeks before your internship ends, it’s clear that the project you were given won’t be finished in time. What do you do?1 minute 30 seconds to answer
Technical questions
- Explain the difference between an inner join and a left join, as if you were talking to a manager who doesn’t use SQL.SQL · 2 minutes to answer
- You’re given a messy spreadsheet of customer orders. Talk me through how you’d clean it before analysing it.Data preparation · 2 minutes to answer
- A dashboard shows sales fell 20% last week. How would you work out why?Analytical thinking · 2 minutes 30 seconds to answer
- What’s the difference between correlation and causation? Give an example from real life.Statistics · 1 minute 30 seconds to answer
- How do you decide which chart to use to show a result, and what mistakes do you try to avoid?Data visualisation · 2 minutes to answer
- A stakeholder asks you for “all the data” on customers. How do you find out what they really need?Stakeholders · 2 minutes to answer
- Walk me through a data project you’re proud of: the question, the data, what you did and what you found.Portfolio · 3 minutes to answer
- A query you wrote is running very slowly. What would you check first?SQL · 1 minute 30 seconds to answer
- Tell me about a business story in the news that has caught your interest recently. Why does it matter, and who does it affect?Commercial awareness · 2 minutes to answer
- A client that runs a chain of coffee shops wants to buy a smaller rival. Apart from the price, what should it think about before agreeing?Commercial awareness · 2 minutes to answer
- Pick a market or economic trend you’ve been following. What’s driving it, and what could change its direction?Market awareness · 2 minutes 30 seconds to answer
- Interest rates rise by one percentage point. Talk me through how that could affect households, businesses and share prices.Economics · 2 minutes to answer
- Would you rather have £1,000 today or £1,100 in two years’ time? Talk me through how you’d decide, including the numbers.Numeracy · 2 minutes to answer
- Explain what happens when someone types a web address into their browser, to a person who has never thought about it.Explaining technical ideas · 2 minutes to answer
- Walk me through a technical project you’ve built or contributed to: what it did, your part, and one decision you’d make differently now.Portfolio · 3 minutes to answer
- A feature works on your machine but fails for some users after release. How would you go about finding the cause?Debugging · 2 minutes 30 seconds to answer
- What’s the difference between ETL and ELT, and when would you choose each?Pipelines · 2 minutes to answer
- Explain idempotency to a new analyst on your team, using a job that runs every night as the example.Pipelines · 2 minutes to answer
- When is a full reload better than an incremental load, and when does it stop being affordable?Pipelines · 2 minutes to answer
- When would you process data in batches, and when would you stream it? Give an example of each.Pipelines · 2 minutes to answer
- How does change data capture differ from taking a nightly copy of a table, and what can go wrong with each?Pipelines · 2 minutes 30 seconds to answer
- What’s the difference between a fact table and a dimension table? Use a cinema’s ticket sales as your example.Data modelling · 2 minutes to answer
- What’s a surrogate key, and why might a warehouse table need one when the source system already has its own ID?Data modelling · 2 minutes to answer
- What is a slowly changing dimension, and when would you keep history with type 2 rather than overwrite the old value?Data modelling · 2 minutes to answer
- How would you test a SQL transformation before it goes into production?Data quality · 2 minutes to answer
- What should a data contract between an application team and a data team say, and how would you check it’s being kept?Data quality · 2 minutes to answer
- Last night’s pipeline finished without errors, but this morning’s dashboard shows about half the usual number of orders. What do you check first?Data quality · 2 minutes 30 seconds to answer
- How do partitioning and clustering work in a cloud data warehouse, and how would a poor choice show up on the bill?Cloud warehouses · 2 minutes to answer
- A year of electricity meter readings is stored as 40,000 small files. Why might queries on it be slow, and what would you do about it?Performance · 2 minutes to answer
- A Spark job is quick on test data, but in production one task runs for hours while the rest finish in minutes. What might be happening, and what would you try?Performance · 2 minutes to answer
- Walk me through a piece of data work you did to a deadline, such as a take-home task or a coursework assignment. What would you change if you had more time?Take-home · 3 minutes to answer
- In a project or take-home task with a loose brief, what assumptions did you have to make, and how did you check them or make them visible?Take-home · 2 minutes to answer
- Pick a project you’ve done. How did you check that your results, or your pipeline, were right before anyone relied on them?Portfolio · 2 minutes to answer
- What’s the hardest bug or data problem you’ve had to track down in a project, and how did you find it?Portfolio · 2 minutes 30 seconds to answer
- Tell me about a project where the data turned out to be different from what you expected. How did you notice, and what did you change?Portfolio · 2 minutes to answer
- If you started your most recent data project again tomorrow, what would you do differently, and why?Portfolio · 2 minutes to answer
- An A/B test shows a new sign-up page lifting sign-ups by 8%. What could make that result misleading, and how would you check before trusting it?Experiments · 2 minutes to answer
- How would you measure customer retention for a subscription app, and why can a single monthly churn rate be misleading?Metrics · 2 minutes 30 seconds to answer
- The marketing team wants to know which channel deserves the credit for each sale. Explain last-click attribution, what it gets wrong, and what you’d suggest instead.Marketing analytics · 2 minutes to answer
- What makes a good north-star metric for a product? Suggest one for a language-learning app, and say how it could go wrong.Metrics · 2 minutes to answer
- A customer has asked why the bank’s scoring model turned down their loan application. How would you help a colleague explain the decision to them in plain English?Explaining models · 2 minutes to answer
- Each morning you need to match yesterday’s 12,000 card payments in your company’s records against the card processor’s settlement report. How would you set up the matching, and what would you do with payments that don’t match?Reconciliation · 2 minutes 30 seconds to answer
- You help prepare a figure that a bank sends to its regulator every quarter. What would you put in place to make sure it’s right, from the source data to sign-off?Data quality · 2 minutes to answer
- You’ve been asked to find out why some customers fall behind on their loan payments, using their bank transactions. How would you work with that data safely?Data protection · 2 minutes to answer
- Explain support, confidence and lift in basket analysis, using a supermarket example, and say why high confidence on its own can mislead.Retail analytics · 2 minutes to answer
- A chain of 200 convenience stores wants to know what would happen if it raised the price of its own-brand sandwiches by 10%. How would you test it?Experiments · 2 minutes 30 seconds to answer
- Why do analysts hide small numbers in published health tables, and how do you stop someone working them out from the totals?Disclosure control · 2 minutes to answer
- What’s the difference between anonymised and pseudonymised data, and why does it matter when you link two health datasets?Data linkage · 2 minutes to answer
- A patient survey says 62% of patients rated their GP practice as good, give or take 5 points, and a practice nearby scored 58%. How would you explain to the first practice’s manager what those figures can and can’t tell her?Statistics · 2 minutes to answer
- A hospital’s managers want a dashboard for their 8am bed meeting. What would you put on it, and how would you make sure it helps them decide what to do?Dashboards · 2 minutes to answer
- A ward’s falls figure for last month was its highest in a year, and the manager wants to know what went wrong. How would you tell whether it’s a real change or normal variation?Statistics · 2 minutes to answer
- Why should analysts use version control for their queries and scripts, and what does good practice with it look like day to day?Ways of working · 2 minutes to answer
- Explain how you’d organise a team’s SQL transformations into layers, with tests, so that people can trust the tables they use.Data quality · 2 minutes to answer
- A report must be refreshed by 6am every day. How would you schedule it, and set up alerts so problems are caught without flooding people with messages?Pipelines · 2 minutes to answer
- You’ve built a dataset that other analysts will use. What would you write down about it, and how would you keep that documentation useful?Ways of working · 2 minutes to answer
- An AI assistant writes you a SQL query that runs without errors and returns a plausible number. How would you check it before you use the result?SQL · 2 minutes to answer
- Pick an engineering principle you know well and explain it to someone with no technical background, using an everyday example.Explaining technical ideas · 2 minutes to answer
- A component keeps failing much earlier than it was designed to. How would you find out why?Root cause analysis · 2 minutes 30 seconds to answer
- How could engineers reduce the carbon impact of a project over its whole life, from design to the end of its use? Use an example you know.Sustainability · 2 minutes to answer
- In about a minute, describe one piece of data work you’ve done: what you were trying to find out, and what came of it.Portfolio · 1 minute to answer
- Pick a business you know as a customer, such as a supermarket, a bank or a streaming service. How do you think it uses data to make decisions, and where could it use data better?Commercial awareness · 2 minutes to answer
- A colleague says a rise in click-through rate from 2.0% to 2.3% is “significant”. What would you ask before agreeing?Statistics · 2 minutes to answer
- A headline says a bus route’s punctuality “rose 5%” when the share of buses on time went from 80% to 84%. Is that fair, and how would you rewrite it?Numeracy · 1 minute 30 seconds to answer
- Explain what a window function does, using a football league table as your example and no code at all.SQL · 2 minutes to answer
- You have two customer lists from different systems and no shared ID. How would you match them, and how would you know how well you’d done?Data preparation · 2 minutes to answer
- Someone emails you a spreadsheet ten minutes before a meeting and asks for the headline number. What checks would you run first?Data quality · 2 minutes to answer
- Explain what a p-value does and doesn’t tell you, to a shop manager deciding whether to keep a new store layout.Statistics · 2 minutes to answer
- Here’s a query: SELECT customers.name, COUNT(*) AS orders FROM customers LEFT JOIN orders ON orders.customer_id = customers.id GROUP BY customers.name. Tell me in plain English what it returns, and one way it could give the wrong answer.SQL · 2 minutes to answer
- When would you do a piece of analysis in Excel, when in SQL and when in Python? Give an example of each.Tools · 2 minutes to answer
- Describe the one-page dashboard you’d build for a café owner who checks it on her phone once a day.Dashboards · 2 minutes to answer
- A director wants a pie chart with fourteen slices on the front page of a report. How do you respond?Data visualisation · 1 minute 30 seconds to answer
- Your team publishes a monthly statistic that the public and the press rely on. This month it has jumped, partly because of a change in how it’s measured. How would you publish it so that people can trust and understand it?Official statistics · 2 minutes to answer
- A council wants to link its housing records with adult social care records to find residents who may need extra support. What would you need to think about to do this safely and lawfully?Data linkage · 2 minutes 30 seconds to answer
- Your organisation wants to publish a year of noise complaints, by street and month, as open data. What would you check before it goes online?Open data · 2 minutes to answer
- Pick a business you know well, such as a gym, a bus company or a supermarket. If its biggest cost rose by a fifth, how would that affect it, and what could it do?Commercial awareness · 2 minutes to answer
- What’s one trend that will change the sector you’re applying to over the next five years, and what should organisations in it be doing about it now?Commercial awareness · 2 minutes 30 seconds to answer
- Think of something you use regularly that costs you nothing, such as an app, a website or a free newspaper. How does the organisation behind it cover its costs and make money?Commercial awareness · 2 minutes to answer
- Pick an organisation you know well. What’s the biggest risk it faces over the next few years, and what would you do about it if you were running it?Commercial awareness · 2 minutes to answer
- How can a business be making a profit and still run out of cash? Explain it with an example.Commercial awareness · 2 minutes to answer
- Data isn’t on your CV as a job title yet. Talk me through the strongest evidence you have that you can already do this work.Portfolio · 2 minutes 30 seconds to answer
- How could what you know about your previous sector help a data team here? Give an example of a question you’d know to ask that a new graduate might not.Domain knowledge · 2 minutes to answer
Brainteaser and estimation questions
- Estimate how many cups of coffee are sold in London on a weekday. Talk through your thinking.2 minutes 30 seconds to answer
- Estimate how many petrol stations there are in the UK. Talk through your thinking.2 minutes 30 seconds to answer
- Estimate how much a multi-storey car park in a city centre earns in a year. Talk through your thinking.2 minutes 30 seconds to answer
- Estimate the size of the UK market for school uniforms, in pounds a year. Talk through your thinking.2 minutes 30 seconds to answer
- Estimate how many GP appointments take place in the UK in a typical week. Talk through your thinking.2 minutes 30 seconds to answer
- Estimate how many bananas a large supermarket sells in a week. Talk through your thinking.2 minutes 30 seconds to answer
- Estimate how many smartphone screens are repaired in the UK each year. Talk through your thinking.2 minutes 30 seconds to answer
- Estimate how many takeaway meals are delivered in Manchester on a Friday evening. Talk through your thinking.2 minutes 30 seconds to answer
Case study questions
- A travel booking site had 400,000 visits last month: 120,000 searched for a trip, 30,000 chose one, 12,000 started to pay and 9,000 booked. The product team wants 10% more bookings. Which step would you look at first, and why?4 minutes to answer
- Daily active users of a food delivery app fell from 200,000 to 176,000 on the day a new version of the app was released, and have stayed there. Orders haven’t changed. How would you investigate?4 minutes to answer
- A streaming service offers a 7-day free trial. About 20,000 people start one each week, and 30% go on to pay. It wants to test a 14-day trial instead. How would you design the test, and how long would it take?4 minutes to answer
- A bank’s new fraud rule flags 2% of the 1 million card payments it handles each day. About 500 of those payments are fraudulent, and the rule catches 400 of them. How good is the rule, and what would you tell the fraud team?4 minutes to answer
- A lender’s share of personal loans in arrears has fallen from 3% to 2% in a year, while the number of loans it holds has doubled from 50,000 to 100,000. The sales director says its lending is getting safer. Do you agree?4 minutes to answer
- A car insurer’s total claims costs rose 15% this year, although it insured about the same number of cars. How would you work out what’s behind the rise?4 minutes to answer
- A supermarket cut the price of a coffee brand from £8 to £6 a jar for four weeks, and weekly sales rose from 4,000 jars to 6,000. Each jar costs the supermarket £5. The promotions team calls it a success. What would you look at before agreeing?4 minutes to answer
- A supermarket’s strawberries sell out by early afternoon most days, but the store manager won’t order more because she’s worried about waste. How would you use data to decide how many to order?4 minutes to answer
- A fashion retailer’s store visits are down 8% on last year, and its online sales are up 15%. The finance director asks whether the stores are becoming less useful. How would you answer?4 minutes to answer
- A toy retailer must decide in March how many units of a new toy to order for Christmas, with no chance to reorder. The toy has no sales history. How would you forecast demand?4 minutes to answer
- A hospital’s waiting list has grown from 40,000 to 43,600 patients in a year, even though it now treats 10,000 patients a month, up from 9,500. How can both be true, and what would you show the board?4 minutes to answer
- A newspaper ranks ten hospitals by the share of hip fracture patients who die within 30 days, and yours is bottom: 27 deaths after 300 operations, 9%, against 7% across all ten. How would you check whether the ranking is fair?4 minutes to answer
- A hospital trust wants to know whether patients from more deprived areas wait longer for hip replacements. How would you find out, and what could make a simple comparison misleading?4 minutes to answer
- A chain of 20 cafés has kept its sales at £10 million a year, but its profit has fallen from £1 million to £400,000 in two years. Staff costs rose by £400,000 and ingredients by £200,000; other costs didn’t change. What would you look into, and what would you recommend?4 minutes to answer
- A cinema chain is considering a five-screen cinema in a town of 90,000 people, where the nearest cinema is 25 miles away. People in similar towns go to the cinema about twice a year. After paying film distributors, the chain keeps about £8 per visit, including snacks. The cinema would cost £4 million to build and £1 million a year to run. Should it go ahead?4 minutes to answer
- A company sells a scheduling app to small businesses for £10 per user per month and has 50,000 paying users. Each user costs about £2 a month to serve. It’s thinking of raising the price to £12. How would you decide whether it should?4 minutes to answer
- A parcel depot has three sorting lines, each handling 2,500 parcels an hour, and works an eight-hour night shift, sorting 60,000 parcels. Before Christmas, volumes are expected to rise by 25%. What options does it have, and what would you recommend?4 minutes to answer
- An airline flies a 180-seat plane on a domestic route twice a day. On average it sells 117 seats per flight at £60 each, and each flight costs £8,000 to run. Is the route making money, and how could it be improved?4 minutes to answer
- A garden centre has sales of £5 million a year: 60% from plants, 25% from its café and 15% from gifts. Most sales come between March and June. The owners want to grow sales by 20% within three years. Where would you look for growth?4 minutes to answer
- Hospital A sees 82% of its A&E patients within four hours, and Hospital B only 74%. Yet B does better for major cases, 60% against 50%, and for minor cases, 95% against 90%. How can both be true, and what would you report?4 minutes to answer
- Your dashboard says online sales last month were £2.4 million, but the finance team’s report says £2.2 million. How would you find out why the two figures differ, and what would you do about it?4 minutes to answer
- A library service has moved bookings for its 40 study rooms online. Before, people booked by phone or at the desk, and about a quarter of booked slots went unused. Which three measures would you track to see whether the change is working, and why those three?4 minutes to answer
- A charity wants to test whether a shorter online donation form raises more money. The form gets about 8,000 visitors a month, 5% of them donate, and the average gift is £30. How would you design the test, and how would you decide when to stop it?4 minutes to answer
- A council wants to know which neighbourhoods need more recycling bins. It has a year of collection records, showing how full each bin was when it was emptied, and 2,000 complaints about overflowing bins. How would you approach it?4 minutes to answer
- A shopping centre had 1.2 million visits last December. So far this year, footfall has been about 4% below the same month last year. How would you forecast this December, and how would you show the manager how uncertain your forecast is?4 minutes to answer
Design questions
- Design the tables for a city’s bike hire scheme so the council can see journeys by station, hour and type of member.Data modelling · 5 minutes to answer
- Design a data model for a parcel carrier so managers can see what share of parcels are delivered on time, by depot, day and delivery service.Data modelling · 5 minutes to answer
- How would you design a table of customers’ addresses so analysts can see where someone lived on any given date?Data modelling · 5 minutes to answer
- A group of GP surgeries wants yesterday’s appointments from three different booking systems in one warehouse by 7am each day. Talk me through the pipeline you’d build.Pipelines · 5 minutes to answer
- Five hundred sensors send a reading every minute, but some readings arrive late or out of order. How would you produce hourly averages that stay right when late data turns up?Pipelines · 5 minutes to answer
- You need to backfill three years of history into a table that already feeds live dashboards. How would you do it safely?Pipelines · 5 minutes to answer
- A supplier sends you a price file every day. Sometimes they send the same file twice, and sometimes a corrected version of an earlier day’s file. How would you design the load?Pipelines · 5 minutes to answer
- A supplier sends you a file every night. What checks would you build so that the pipeline stops, rather than publishes, when the file is broken?Data quality · 5 minutes to answer
Presentation questions
- You’re a graduate analyst at a personal loans company. About 4,000 customers a month miss a payment, and every one of them is phoned, at £12 a call. 60% pay within 30 days, and the company’s analysis suggests most of them would have paid without a call. Of the rest, about 400 a month end up in default, costing an average of £1,500 each. The collections director has three ideas: a text with a link to pay, at 20p each, sent before any call; a model that predicts who will pay without help, so that only the others are phoned, costing £60,000 to build; or a specialist team of six for customers in financial difficulty, costing £240,000 a year. Prepare a five-minute presentation recommending what to do.5 minutes to answer
- You’re a graduate analyst at an online fashion retailer. It sold 2 million items last year, and 30% were returned, up from 25% the year before. Each return costs £5 to process. Dresses are returned 45% of the time and all other items 20%, and dresses have grown from a fifth to two fifths of the items it sells. Half of all returns are for poor fit. The customer director has three ideas: charging £1.50 for each return, although a third of customers in a survey said they’d then shop less; a size advice tool costing £250,000 a year, which cut fit returns on dresses by a fifth in a trial; or better measurements and photos for the 200 most-returned products, which account for a fifth of returns, costing £80,000 once. Prepare a five-minute presentation recommending what to do.5 minutes to answer
- You’re a graduate in a town council’s regeneration team. High street footfall has fallen 18% in five years, and 12 of its 80 shops are empty. The council has £400,000 and two options: pedestrianise the main street with seating and planting, costing £380,000 once; or two hours’ free parking plus a monthly market for three years, costing £130,000 a year. A shopper survey found 40% arrive by car, and most shopkeepers fear losing passing trade if cars are removed. Prepare a five-minute presentation recommending one option to councillors.5 minutes to answer
- You’re a graduate analyst at a chain of 12 bookshops. Sales have fallen from £9 million to £7.6 million in three years, and only 3% of them are online. The managing director has £250,000 to invest and three ideas: a better website with click and collect; cafés in the four busiest shops, which make half of all sales; or author events and children’s reading clubs, since event visitors spend twice as much. Prepare a five-minute presentation recommending how to spend it.5 minutes to answer
- You’re a graduate in the operations team of a delivery firm with 50 diesel vans, whose leases end over the next two years. Electric vans would cost £8,000 more each to lease over four years, but save about £3,500 a year each on fuel and maintenance. Depot chargers would cost £120,000. Most routes are about 90 miles a day, well within an electric van’s winter range of 130 miles, but eight rural routes are over 140. Prepare a five-minute presentation for the directors recommending what to do.5 minutes to answer
- You’re a graduate at a charity that runs food banks in three towns. Its volunteers have fallen from 400 to 250 in two years. Half of those who left had volunteered for under six months, and their top reasons were inflexible shifts, feeling unappreciated and poor training. The charity can spend £20,000 on the problem this year. Prepare a five-minute presentation for the trustees setting out your plan to recruit and keep volunteers.5 minutes to answer
- You’re a graduate analyst at a chain of 30 bakeries. The bread and cakes it throws away cost £1.2 million a year to make. Waste is 22% of what’s baked in its eight railway station shops and 11% in the other 22 shops. The operations director has three ideas: half price on everything left after 5pm, which cut waste at two station shops from 22% to 13% in a four-week trial, though full-price sales there dipped; baking twice a day in smaller batches, which needs £5,000 of equipment per shop and which the head baker expects to cut waste by a third; or giving leftovers to a food charity, which costs nothing but saves no money. Prepare a five-minute presentation recommending what the chain should do.5 minutes to answer
- You’re a graduate analyst at a hospital trust. Last year 36,000 of its 400,000 outpatient appointments, 9%, were missed without warning, up from 6% three years ago. The trust estimates each one wastes £120 of clinic time. Missed appointments are highest among 18 to 30 year olds (15%) and for slots before 9am (13%). In a three-month trial, text reminders sent two days before cut missed appointments in the skin clinic from 10% to 6%. Texts cost 4p each, and the trust has mobile numbers for 80% of patients. An online system for patients to cancel and rebook would cost £90,000 to set up. Prepare a five-minute presentation recommending what the trust should do.5 minutes to answer
- You’re a graduate analyst at an energy supplier with 300,000 customers. Calls to its helpline rose from 40,000 to 52,000 a month this winter, and the average wait is now 14 minutes. Of those calls, 45% are about bills, 25% about meter readings, 15% about moving home and 15% about other things. Two thirds of the meter reading calls come from customers without a smart meter. The customer director has £500,000 and three options: 15 more call handlers for a year (£450,000); a better online account where customers can send readings and see their bill explained (£350,000); or a campaign to book smart meter fittings for the 20,000 customers who call most (£150,000). Prepare a five-minute presentation recommending what to do.5 minutes to answer
- You’re a graduate analyst at a bus company that can add two buses to its network from January, at £150,000 a year each. Route 3 carries 2,400 passengers a day but runs on time only 74% of the time, mostly because of roadworks due to finish in March. Route 11 carries 1,500 a day, and at peak times about 120 people a day are left at stops because buses are full. Route 20, a new route to a business park, carries 300 a day and has grown by 10% a month since it started in June. The average fare is £2. Prepare a five-minute presentation recommending where the two buses should go.5 minutes to answer
How to prepare
From reading
Reading about a question is a start. Answers improve when you plan them from your own experience and then say them out loud.
Learn what each type is testing
Read the guide to each question type, so you know what the interviewer is listening for and which structure fits.
Collect your stories
Six to eight real examples from your degree, work, volunteering and the rest of your life can cover most competency and values questions.
Outline, don’t script
Note the key points of each answer. Scripts sound recited and fall apart when an interviewer asks a follow-up question.
Practise out loud, against the clock
Saying an answer with thinking time and a time limit shows you where it runs long or loses its thread.
Want a day-by-day route? See the study plans for data and graduate interviews
Want to go deeper? Our interview guides work through full example answers, the follow-up questions to expect and a checklist for each.
- 10 min read
STAR method examples: six worked answers for graduates
Six complete worked answers, how long each part should take, and how to build your own story bank.
- 7 min read
Competency, strengths or values interview? How to tell, and how to answer each
How to spot each style, and one experience answered three different ways.
- 6 min read
How to handle follow-up questions in an interview
The six kinds of follow-up question, why interviewers ask them, and how to stay steady.
These guides are general practice advice written by Deeplink. They aren’t linked to any employer, and our feedback is practice guidance, not a prediction of any hiring decision. How we write and check our questions.