CRIF · Data Scientist
Updated · 2026-09-24

CRIF Data Scientist
Interview Questions & Guide 2026

THE 60-SECOND BRIEF

As a Data Scientist at CRIF, you are at the heart of the "Innovation Drive," the company's dedicated center of excellence. Your work directly influences the global financial ecosystem by designing, developing, and maintaining advanced AI and GenAI systems. You will bridge the gap between complex theoretical modeling and production-grade solutions, impacting how banks, insurance companies, and enterprises manage risk, credit scoring, and customer relationships.

In modelling rounds the live question is usually why this model class for this problem, and how you would know six weeks after launch that it is still working. Deriving gradients by hand is rarely what is being probed.

CRIF candidates report 2 rounds · ≈ 2-4 weeks. The stages below are what candidates describe, not a published process.

Analyse at the account grain, cluster errorsRead NRR on a fixed account cohortStrip CI, retry and synthetic traffic first

27 min read

Browse Data Scientist questions

See the practice prompts

13Practice promptsAcross five skill areas
3With worked solutionsIncluded in the practice prompts

As a Data Scientist at CRIF, you are at the heart of the "Innovation Drive," the company's dedicated center of excellence. Your work directly influences the global financial ecosystem by designing, developing, and maintaining advanced AI and GenAI systems. You will bridge the gap between complex theoretical modeling and production-grade solutions, impacting how banks, insurance companies, and enterprises manage risk, credit scoring, and customer relationships.

This role is both technically rigorous and strategically significant. You will not only build models but also participate in the end-to-end lifecycle, from experimentation and LLM fine-tuning to deploying scalable MLOps architectures. Whether you are working on RAG systems, vector databases, or traditional predictive models, you will collaborate with cross-functional teams of Data Engineers and Cloud Engineers, ensuring that your data-driven insights translate into tangible business value.

The "Innovation Drive" team values a mix of academic rigor and practical engineering. Expect to be evaluated not just on your ability to select an algorithm, but on your ability to productionize your ideas.

01

Screening Call

reported

Most candidates lose this call inside the first two minutes, during the walkthrough of their own background. The account runs chronologically, sits at the level of tools and titles, and never arrives at a decision anyone could have disagreed with. Anchor on a problem instead of a timeline: what the team could not answer, what you did about it, what happened next. Ninety seconds is enough, and stopping on time leaves room for the half of the call that belongs to you. What you ask about how work gets prioritised signals your level more reliably than the walkthrough does.

What to demonstrate

  • Whether your background summary has a shape (problem, decision, consequence) or is a chronological list of tools and employers
  • Whether you can account for gaps, short stints and the reason you are looking, unprompted and without hedging
  • The substance of the questions you ask back, which an experienced screener reads as a level signal

How to prepare

  • Time your opening walkthrough against a clock. If it runs past two minutes, compress the earliest role into a single clause and spend the recovered time on the most recent one
  • Write one honest sentence for every gap or short stint visible on your resume and offer it before being asked about it
  • Prepare questions about how work arrives and gets prioritised: who writes the request, how often priorities change, and what happens to an analysis after it is delivered
PracHub interview research ↗
02

Technical Evaluation

reported

A handful of shapes account for most of what gets asked in this format: a ranking or deduplication inside groups, a running or rolling total, a period-over-period comparison, and a cohort tracked forward over time. Recognising the shape quickly is most of the speed here; deriving it from scratch while a clock runs is where the time goes. Know that a window function keeps every row while a GROUP BY collapses them, and know which one the question needs. If the exercise is in Python instead of SQL, the same shapes arrive as groupby with transform, shift and merge, and the same grain mistakes are available.

What to demonstrate

  • Whether you reach the right construct without a detour, such as ROW_NUMBER over a partition to deduplicate instead of a self-join against a MAX subquery
  • Whether you know what your window frame actually is, since adding ORDER BY inside OVER changes the default frame and silently changes a running total
  • Whether the thing runs. A near-miss that throws an error scores below a plainer query that returns the right rows.

How to prepare

  • Write each of the four shapes once from memory against a small schema and keep the working version somewhere you will reread it: dedupe with ROW_NUMBER, a running total, a month-over-month change with LAG, and a retention table
  • Compute one running total twice on data with tied timestamps, once on the default frame and once with ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW, and look at where the two disagree
  • If Python is on the table, rebuild the dedupe and the running total with groupby and cumsum, then assert the two implementations return identical rows
PracHub interview research ↗

PracHub editorial advice for the preparation topics above.

01

Randomising an experiment at the user level when users share an account

Two problems fire at once. Colleagues in one workspace see each other's work and talk to each other, so a treated user changes the behaviour of a control user in the same account, which violates the no-interference assumption and biases the estimate toward zero. Separately, outcomes within an account are strongly correlated, so the effective sample size is roughly n / (1 + (m - 1) * rho) for m users per account and intra-class correlation rho, not n. With rho around 0.3 and twenty users per account that is a design effect near 6.7, meaning a user-level confidence interval is about two and a half times narrower than it should be and results cross significance thresholds on noise alone. Randomise the account and cluster the standard errors.

02

Reading consumption metrics before the metering lag window has closed

Usage pipelines land late and correct themselves, which is exactly what is_restated and restated_at record. A dashboard queried on day T sees a partially populated tail for the last several days, so the most recent points always slope downward and always look like a regression. Analysts then explain the artefact, and sometimes ship a change to fix it. Establish the empirical settling time by measuring how much a given usage_date's total moves between first_written_at and its final value, exclude that many trailing days from every reportable figure, and never compare a fresh period against a settled one.

03

Generalising beyond the population the sample actually supports

State the frame the sample was drawn from and where it diverges from the population you want to talk about: time window, platform, geography, opt-in. If a group is excluded from the frame, either weight to known margins or narrow the claim rather than quietly extending it.

04

Averaging per-user rates to produce a population rate

Decide which quantity you want: the mean of per-user ratios and the ratio of summed numerator to summed denominator are different estimands, and heavy users dominate one but not the other. For a ratio metric, aggregate numerator and denominator separately and use the delta method for its variance.

Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.

10 technical prompts3 include a worked solution

Walk me through a logical reasoning puzzle (e.g., probability or seque…

medium
statistics and probability

Walk me through a logical reasoning puzzle (e.g., probability or sequence-based).

Approach
  1. Say what the estimate is of, and over what population it generalises.
  2. Quantify uncertainty explicitly rather than reporting a point estimate alone.
  3. Sanity-check the answer against a simple bound or a simulated case.
Follow-up
  • What sample size would you need to detect an effect half this size?
  • How would you explain this result to someone who does not know statistics?

Can you explain the difference between an embedding model and a standa…

medium
machine learning and modelling

Can you explain the difference between an embedding model and a standard regression model?

Approach
  1. Frame the prediction: the label, the moment of prediction, and the action it triggers.
  2. Say how the offline result would be validated online before it is trusted.
  3. Pick an evaluation metric that matches the cost of each error type, not a default.
Follow-up
  • Where could label leakage enter this setup?
  • What would you monitor after launch to know the model is still valid?

How would you approach debugging a model that is performing poorly in …

medium
machine learning and modelling

How would you approach debugging a model that is performing poorly in production?

Approach
  1. Set a baseline first, so any model has something honest to beat.
  2. Frame the prediction: the label, the moment of prediction, and the action it triggers.
  3. Check what information would not exist at prediction time, and exclude it.
Follow-up
  • Where could label leakage enter this setup?
  • How would you choose the decision threshold, and who owns that choice?

What is your process for selecting the right features for a predictive…

medium
machine learning and modelling

What is your process for selecting the right features for a predictive model?

Approach
  1. Say how the offline result would be validated online before it is trusted.
  2. Pick an evaluation metric that matches the cost of each error type, not a default.
  3. Frame the prediction: the label, the moment of prediction, and the action it triggers.
Follow-up
  • Where could label leakage enter this setup?
  • What would you monitor after launch to know the model is still valid?

Sessionise an API event stream with a 30-minute inactivity gap

mediumWorked solution
sessionisationevent-streamspandas

fct_api_request arrives as a DataFrame with account_id, user_id, request_at (tz-aware UTC), traffic_class and http_status, roughly 5 million rows. Assign a session_id to every human-attributable request: drop rows where user_id is null or traffic_class is in ('ci','synthetic_monitor','load_test'), then open a new session whenever the gap since that user's previous remaining request exceeds 30 minutes. Return the filtered frame plus session_id, and a per-session summary with user_id, account_id, session start, session end and request count. Do not loop over rows.

Approach
  1. Settle the filter-then-gap ordering before writing code. Removing CI and synthetic rows changes the gaps, so sessionising the raw stream and filtering afterwards is a different answer; the definition given filters first, and the two diverge most for accounts whose CI runs every ten minutes.
  2. Sort once by (user_id, request_at) with a stable kind, then gap = df.groupby('user_id', sort=False).request_at.diff(). The first row of each user yields NaT, which is exactly the boundary condition you want rather than a special case to patch.
  3. new_session = gap.isna() | (gap > Timedelta(minutes=30)); session_id = new_session.cumsum(). The cumsum runs over the whole sorted frame and therefore produces globally unique ids in one pass; a per-user cumcount collides across users and forces a composite key on every downstream join.
  4. Build the summary with a single groupby('session_id').agg(...). user_id and account_id can be carried with 'first' only because the sort key groups them — state that dependency, since it silently breaks if someone later re-sorts the frame.
  5. Decide explicitly what a session means when one user_id holds memberships in several accounts: either add account_id to the sort and group keys, or document that sessions may cross accounts. Leaving it undecided produces sessions whose account_id is whichever row sorted first.
Worked solution 30 min
  1. human = df[df.user_id.notna() & ~df.traffic_class.isin(['ci','synthetic_monitor','load_test'])].sort_values(['user_id','request_at'], kind='mergesort').reset_index(drop=True)
  2. gap = human.groupby('user_id', sort=False).request_at.diff(); human['session_id'] = (gap.isna() | (gap > pd.Timedelta(minutes=30))).cumsum()
  3. summary = human.groupby('session_id').agg(user_id=('user_id','first'), account_id=('account_id','first'), start=('request_at','min'), end=('request_at','max'), n_requests=('request_at','size')).reset_index()
  4. assert summary.n_requests.sum() == len(human) and human.groupby('session_id').user_id.nunique().max() == 1
EXPECTED RESULThuman gains a dense session_id increasing in (user_id, request_at); summary has exactly one row per session, n_requests sums to len(human), and every within-session consecutive gap is at most 30 minutes while every same-user between-session gap exceeds it.
Follow-up
  • Where does 30 minutes come from, and how would you pick it from this data instead of from convention?
  • An engineer reused their personal key for a nightly batch job, so machine traffic carries a human user_id. How would you detect that, and should those requests form sessions?
  • How much does the session count change if you sessionise before dropping CI traffic rather than after?

Instead of guessing where the week should go, day one measures it under a fixed rubric and allocates the remaining hours in proportion to the gaps. The method is deliberately rigid: the allocation is written down before any studying starts and is not renegotiated when a topic turns out to be unpleasant.

Small steps. Visible outcomes.0 / 7 completed
ONE WEEK · YOUR PACE

Prepare, practise & reflect

One practical outcome each day. Spend longer where you need it.

0 / 7 done
01Diagnostic, scored before you study anything
  • Sit a 100-minute timed diagnostic in four blocks: 30 minutes of SQL across three prompts, 25 minutes of short-answer statistics, 25 minutes on one modelling or case prompt, and 20 minutes delivering one behavioural story aloud.
  • Score each block from 0 to 3 on a fixed rubric where 3 is correct and fluent, 2 is correct but slow or prompted, 1 is partially correct, and 0 is stuck, grading the output rather than how the attempt felt.
  • Allocate the hours for days two to five roughly in proportion to 3 minus the score in each block, write the allocation down, and commit to not revising it midweek.

Deliverable: A scored rubric and a fixed hour allocation for the rest of the week.

Practice prompt ↗Practice prompt ↗Worked solution ↗
02Largest gap: find the boundary rather than the subject
  • Break the weakest area into five named sub-skills (for query work: grain control, window frames, date arithmetic, set logic with NULLs, and reading a query plan) and rate each one, so the rest of the week targets a sub-skill instead of a subject.
  • Solve three problems chosen to sit just above where the rating drops off, and for each write the first move you failed to make.
  • Re-solve one of them from memory four hours later, on paper, with nothing open.

Deliverable: A five-item sub-skill map with the two blocking sub-skills circled.

Practice prompt ↗Practice prompt ↗
03Largest gap: drill the blocking sub-skill
  • Do eight short repetitions of the same shape rather than eight different problems, so what you practise is the pattern and not the puzzle.
  • Write the rule you now hold in one sentence, then test it against a case built to break it: a ranking function over a column with ties, or a two-sample test on observations that are obviously dependent.
  • Have someone else read your one-sentence rule and find the precondition you left out.

Deliverable: One rule statement with its preconditions attached and one counterexample that would have caught the incomplete version.

Practice prompt ↗Practice prompt ↗
04Second gap, plus maintenance on your strongest area
  • Run the same sub-skill map and boundary protocol on the second-largest gap, compressed into half the day.
  • Spend 25 timed minutes on your strongest area to stop it decaying, choosing the hardest problem you can still finish rather than an easy warm-up.
  • Compare how the two areas fail: whether you lose time on recall, on setup, or on arithmetic, because the fix differs for each.

Deliverable: A second sub-skill map plus a one-line diagnosis of how each area fails you.

Practice prompt ↗Practice prompt ↗Worked solution ↗
05The gap that is not a skill
  • Record yourself answering one technical and one behavioural prompt, then count two things in the playback: how many seconds before your first clarifying question, and how many sentences you started without knowing where they ended.
  • Rewrite your three most-used stock phrases into shorter versions, and practise saying "I do not know, here is how I would find out" without softening it into a guess.
  • Deliver one answer again with a hard 90-second limit to force structure before detail.

Deliverable: Two recordings with a counted improvement in time-to-first-question.

Practice prompt ↗Practice prompt ↗
06Retest under day-one conditions
  • Sit the same 100-minute diagnostic structure with new prompts of comparable difficulty and score it on the identical rubric.
  • Compare block by block, and for any block that did not move, change the method rather than adding hours: a block stuck at 1 usually means the practice was too varied, not too short.
  • Write which single block you would still lose the offer on.

Deliverable: A second scored rubric placed next to the first, with one named remaining risk.

Practice prompt ↗Practice prompt ↗
07Full loop under interview conditions
  • Run a 60-minute mock covering the two blocks that moved least, with an interviewer instructed to interrupt and change direction.
  • Write your recovery script for the moment you go blank: restate the question, state your assumption, name the first thing you would check.
  • Reduce the week to the rule statements you wrote, each with its preconditions attached, then say every one of them out loud without reading it and cut any you cannot state in a single sentence, since a rule you have to reconstruct mid-answer will not survive being interrupted.

Deliverable: A one-page card holding the recovery script and only the rules you could state from memory.

Practice prompt ↗Worked solution ↗

Expand any day for tasks and deliverables. Your progress is saved on this device.

An answer without a quantity is hard to interrogate, so interviewers keep probing until they find one. Come with the baseline, the change, the window it was measured over, and how confident you were. If the effect never got measured, say so and say what you would have measured. Fabricated precision is worse than an honest gap.

How do you manage high workloads and conflicting priorities within a t…

medium
behavioural and stakeholder questions

How do you manage high workloads and conflicting priorities within a team?

Approach
  1. Name the disagreement or constraint, and how you resolved it with evidence.
  2. Pick a story where you drove the decision, not one where you observed it.
  3. Close with what you would do differently, concretely.
Follow-up
  • What did you decide not to do, and why?
  • What would you do differently if you ran that project again?

How do you handle imbalanced datasets in a classification problem?

medium
behavioural and stakeholder questions

How do you handle imbalanced datasets in a classification problem?

Approach
  1. State the situation in two sentences and spend the rest on your reasoning.
  2. Name the disagreement or constraint, and how you resolved it with evidence.
  3. Quantify the outcome, including what you would not claim credit for.
Follow-up
  • What would you do differently if you ran that project again?
  • How did you know the outcome was caused by your change?

Allocate one analyst week across three competing requests

easy
prioritisationstakeholdersscoping

Three requests arrive the same morning and you have one week. Finance wants per-account gross margin from fct_usage_daily for a pricing review in three weeks. Sales wants a renewal-risk list for accounts with term_end_date inside 60 days. A product manager wants an experiment readout for a decision being taken on Thursday. Produce your allocation with hours attached, what you say to whoever receives less, and one thing you refuse to do this week, with the reason each decision is defensible to the person it costs.

Approach
  1. The interviewer is probing whether you prioritise on decision timing and reversibility or on who asked most forcefully. Sort by the date each decision is actually taken and by what the default outcome is if nothing arrives.
  2. Apply that sort concretely. The Thursday readout has a hard irreversible deadline and no value afterwards. The pricing review has three weeks of slack. The renewal list has a rolling deadline set by term_end_date, so part of it is urgent this week and the rest is not, which means it can be split rather than deferred whole.
  3. Find the cheapest sufficient version of each request rather than the full version. The readout goes in full. The renewal list ships as a filtered query over renewal-eligible accounts ranked by two inspectable signals rather than as a model. The margin work is scoped to the accounts that dominate the pricing decision, since revenue is heavily skewed and the tail will not change the conclusion.
  4. Make the trade visible in one written note to all three at once, with dates. Telling each person separately that they are the priority is how an allocation becomes a credibility problem.
  5. Refuse something explicitly and say why. The model version of the renewal list is the usual candidate, because it cannot be evaluated without a holdout nobody has agreed to yet, and building it this week forecloses that.
  6. Leave slack. A plan with none is a plan to miss the one deadline that cannot move.
Follow-up
  • The sales leader escalates to your manager. What did you already do that makes that a short conversation?
  • Which of the three deadlines would you push back on, and what exactly would you ask for?
  • What would you change about how these requests reach you so next week is not the same?
  • 01

    How do you manage high workloads and conflicting priorities within a team?

  • 02

    How do you handle imbalanced datasets in a classification problem?

  • 03

    Three requests arrive the same morning and you have one week. Finance wants per-account gross margin from fct_usage_daily for a pricing review in three weeks. Sales wants a renewal-risk list for accounts with term_end_date inside 60 days. A product manager wants an experiment readout for a decision being taken on Thursday. Produce your allocation with hours attached, what you say to whoever receives less, and one thing you refuse to do this week, with the reason each decision is defensible to the person it costs.

PracHub interview preparation framework ↗
Is this an official CRIF interview guide?

No. It is PracHub's own research and practice material for the Data Scientist role at CRIF. Rounds and questions reflect what candidates have reported, not a process CRIF has published, and they change over time. Confirm the current format and scope with your recruiter.

PracHub interview research ↗
How difficult are the technical tests?

Candidates generally describe the difficulty as average to manageable. The key is not to solve every problem perfectly but to show a logical, structured approach to problem-solving.

PracHub interview research ↗
What is the company culture like?

CRIF is described as a professional, innovative, and international environment. They emphasize growth, inclusivity, and a "think outside the box" mentality.

PracHub interview research ↗
How long does the entire process take?

While it varies, the process moves efficiently. You can expect to hear back from recruiters relatively quickly after each stage, with the entire cycle often concluding within a few weeks.

PracHub interview research ↗
Should I prepare for remote or in-person interviews?

Be prepared for both. The process often starts with a phone screen, followed by online or in-person technical interviews, depending on your location and the team's preference.

PracHub interview research ↗
Sources & methodology 3 sources ↗

No official company page is cited. Rounds and questions come from candidate reports and PracHub editorial material; each source shows the date it was read.