As a Data Scientist at Compass, you sit at the intersection of high-stakes real estate technology and advanced machine learning. Your work directly influences how agents operate, how properties are priced, and how millions of users discover their future homes. You are not just building models; you are architecting the data-driven infrastructure that powers a transformative platform in a traditionally opaque industry.
The role demands a balance of rigorous technical execution and product-minded intuition. You will tackle complex problems—such as predictive modeling for market trends, search and recommendation algorithms, and internal operational efficiency—at a significant scale. At Compass, success is measured by your ability to translate ambiguous business challenges into actionable insights and scalable, production-ready solutions.
The interview process is rigorous and can be lengthy. Expect multiple rounds of internal evaluation that prioritize both your technical depth and your ability to communicate complex findings to non-technical stakeholders.
Preparation focus
editorialNo round sequence has been reported for this company, so work the categories below and confirm the format with your recruiter.
What to demonstrate
- Breadth across SQL, experimentation and product reasoning
- Ability to state assumptions before choosing a method
How to prepare
- Drill the practice exercises below and time yourself
- Prepare three quantified stories about decisions you drove
PracHub editorial advice for the preparation topics above.
Slicing a flat experiment until a segment reaches significance
Testing one metric across twenty segments at a nominal 5% level produces a significant result about two thirds of the time when nothing is happening anywhere, and the segment that surfaces is by construction the one with the most favourable noise. The reported effect in that slice is then badly overstated, because selection on significance conditions the estimate on being large. What makes it dangerous rather than merely wrong is that a post-hoc segment always has a plausible story attached, so it survives the meeting. The controls are declaring the small number of segments of interest before launch, correcting across the ones tested, and treating anything discovered afterwards as a hypothesis that needs its own adequately-powered test rather than a finding.
Comparing cohort retention curves of different maturities, or building the curve from users who are still present
A cohort four weeks old has no week-8 value, so an average taken across cohorts silently drops young cohorts from the later columns and keeps them in the earlier ones. The curve then bends upward at the tail, and the reading that 'retention is improving over time' is an artefact of which cohorts survived to be measured. The same error appears in the denominator when retention is computed over users active in the current period rather than over the full original cohort, which conditions on survival and guarantees a flattering number. The fix is a triangle: fix the cohort at signup, bound every window on both sides, and only compare cells where every cohort has had the full elapsed time, publishing the rest as blank rather than as a partial average.
Answering a product-sense question with a list of features
Answer with a decision and the measurement that would settle it: the hypothesis, the primary metric, the guardrails, and the result that would make you not ship. A feature brainstorm cannot be wrong, which is exactly why it earns no points.
SQL that silently fans out on a one-to-many join
State the grain of each table and the grain you want in the result before writing the join. Pre-aggregate the many side to the join key, or use EXISTS or a window function, and verify with a row count against COUNT(DISTINCT id) rather than trusting that the numbers look plausible.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
How would you design a recommendation system for property listings?
How would you design a recommendation system for property listings?
Approach
- Sanity-check the answer against a simple bound or a simulated case.
- Translate the result into the decision it informs, in one plain sentence.
- Write down the assumption the method needs before you use the method.
Follow-up
- How would you explain this result to someone who does not know statistics?
- What sample size would you need to detect an effect half this size?
Explain the trade-offs between different loss functions in a regressio…
Explain the trade-offs between different loss functions in a regression model.
Approach
- Check what information would not exist at prediction time, and exclude it.
- Pick an evaluation metric that matches the cost of each error type, not a default.
- Say how the offline result would be validated online before it is trusted.
Follow-up
- How would you choose the decision threshold, and who owns that choice?
- Where could label leakage enter this setup?
Describe the process of feature selection and how you evaluate model p…
Describe the process of feature selection and how you evaluate model performance beyond simple accuracy.
Approach
- Pick an evaluation metric that matches the cost of each error type, not a default.
- Say how the offline result would be validated online before it is trusted.
- Frame the prediction: the label, the moment of prediction, and the action it triggers.
Follow-up
- How would you choose the decision threshold, and who owns that choice?
- What would you monitor after launch to know the model is still valid?
Audit a one-day event extract for structural defects
You receive a one-day extract of fct_event as a DataFrame with event_id, occurred_at_utc, received_at_utc, visitor_id, user_id, account_id, event_name, is_bot_flagged and surface. Write a function returning one row per data-quality rule with the rule name, the failing row count and the failing share of the extract. Cover at minimum: duplicate event_id, received_at_utc earlier than occurred_at_utc, occurred_at_utc later than the extract's maximum received_at_utc, account_id present while user_id is NULL, and rows whose occurred_at date differs from their received_at date. Do not drop rows; report only.
Approach
- Compute the extract's own reference clock first: max(received_at_utc). Wall-clock now() is wrong here because the extract may be replayed days later, which would turn every row into a future-dated failure.
- Express each rule as a boolean Series over the same index so the checks compose, then aggregate with .sum() and divide by len(df). Building a list of (name, mask) pairs keeps the rule set extensible and keeps one code path for counting.
- For the duplicate rule, decide and state the convention: df.duplicated('event_id', keep=False).sum() counts every member of a duplicated group, df.duplicated('event_id').sum() counts only the surplus copies. Either is defensible; an unstated choice is not. The rest of this item assumes keep=False.
- Treat received_at < occurred_at as clock skew, not corruption: occurred_at is client-supplied. Separate it from the date-mismatch rule, which is the one that actually breaks a daily metric keyed on occurred_at.
- Know which rules imply which before you read the counts. A row whose occurred_at exceeds max(received_at_utc) has its own received_at no later than that maximum, so it is necessarily a clock-skew row as well: the future-dated mask is a subset of the skew mask, always. Neither is a subset of the date-mismatch mask, because skew of a few minutes inside one UTC date mismatches nothing.
- Return a tidy DataFrame sorted by failing_share descending, and add a boolean column saying whether the rule should block publication, so the output is a decision rather than a list of numbers.
Worked solution 20 min
- Parse both timestamp columns with utc=True and assert the dtype, since a silently-object column makes every comparison string-wise and wrong.
- Set ref = df['received_at_utc'].max() and build the five masks against it.
- Assemble results as pd.DataFrame(rows) with columns rule, failing_rows, failing_share, blocks_publication.
- Keep the masks addressable (a dict of name to Series) rather than only their sums, so the overlap between rules can be asserted rather than assumed.
- Verify the function is pure: assert the input frame's shape is unchanged after the call.
Follow-up
- The date-mismatch count is 2.1 percent on this extract. What late-arrival rule would you write for a daily metric, and how many days would you hold the number open?
- Duplicate event_id values appear only on the 'core_action_completed' event. What upstream cause would you check before deduplicating?
- Which of these rules should fire an alert at the pipeline, and which should only appear in a weekly review?
Write a function to calculate the moving average of a list of time-ser…
Write a function to calculate the moving average of a list of time-series data.
Approach
- Compute rates by summing numerator and denominator separately, never by averaging rates.
- State the window function and its partition and ordering out loud before writing it.
- Handle the rows that do not match: a LEFT JOIN with a NULL check is usually the question.
Follow-up
- What breaks if events arrive late or out of order?
- How would you verify this result without re-running the same query?
Attribute account MRR to first-touch channel without seat fan-out
dim_user holds user_id, account_id, first_touch_channel, account_created_at_utc. dim_account holds account_id, lifecycle_status. fct_subscription_period holds account_id, period_start_utc, period_end_utc, period_status, mrr_cents_constant_fx. For a given as-of date, report active MRR by the first-touch channel of the account's earliest-created user. An account has many users and many periods. The channel totals must sum exactly to total active MRR on that date, and accounts whose label is NULL must appear as their own bucket.
Approach
- Reduce the label side to one row per account before any join: ROW_NUMBER() OVER (PARTITION BY account_id ORDER BY account_created_at_utc, user_id) = 1 over dim_user, carrying first_touch_channel. Joining dim_user to the period table directly repeats each revenue row once per seat.
- Reduce the money side to one row per account too: the period where period_start_utc <= :as_of AND period_end_utc > :as_of AND period_status IN ('active','past_due'). If more than one row survives that filter the account holds overlapping subscriptions, which must be deduped or deliberately summed, and either way the choice is stated rather than left to the join.
- Join the two one-row-per-account CTEs and SUM(mrr_cents_constant_fx). Use the constant-FX column, since the same query run in two quarters otherwise reports currency moves as channel performance.
- Bucket NULL first_touch_channel as 'unattributed' with COALESCE instead of letting it drop. Roughly the share of users with no observed touch is not small, and dropping it understates the total and inflates every named channel's share.
- Reconcile: the SUM over the joined result must equal the SUM over the period CTE alone. That single equality check catches fan-out immediately, which is why it is worth writing before presenting the number.
Worked solution 30 min
- Compute total active MRR on the as-of date from the period table alone and write the number down as the target.
- Build the label CTE and assert COUNT(*) = COUNT(DISTINCT account_id).
- Build the as-of period CTE and assert the same, investigating any account with more than one surviving row.
- Join, COALESCE the channel, aggregate, and compare the total to the target.
- Deliberately run the naive dim_user join and record the inflation factor, which is the MRR-weighted mean seat count.
Follow-up
- Which user should own the account's label: earliest created, the 'owner' role, or the one who converted? What does each choice systematically favour?
- What does this table entitle you to say about the value of a channel, and what does it not?
- Some accounts have a parent_account_id. How does rolling those up change both the numerator and the channel mix?
Define success for a rebuilt first-run onboarding checklist
A rebuilt first-run checklist ships to all new signups next month. You have dim_user (user_id, account_created_at_utc, signup_surface, is_internal) and fct_event (user_id, occurred_at_utc, is_core_action, event_name, surface). Propose a primary metric with an explicit numerator, denominator, window and publication lag, plus two guardrails and one diagnostic you would refuse to treat as success. The team wants a number it can read weekly, and the constraint is that everything must be computable from those two tables alone. Deliver the metric tree from the north star down to the metric you chose.
Approach
- Fix the grain and the cohort key first: the checklist is seen by users, so count on user_id with account_created_at_utc as the cohort key, and say out loud that the north star is account-grained so the tree crosses grains here deliberately rather than by accident.
- Take seven-day activation as the primary — core action on at least 2 distinct UTC dates inside [account_created_at_utc, +7 days) — because the two-distinct-days predicate cannot be satisfied by the single checklist-completion click the feature itself produces.
- Demote checklist completion rate to a diagnostic and give the reason: it is an output of the feature, so it is near-perfectly correlated with having shipped the feature and cannot fall when the feature is bad.
- Pick guardrails by the failure each one catches, not by what is easy to query: week-4 signup-cohort retention catches an activation gain that does not persist, and p50 minutes to first core action catches a checklist that adds steps to a path users already completed.
- State the operational rules explicitly: is_internal = FALSE, an 8-day publication lag, and signup_surface values 'invite' and 'sso_provisioned' split out because those users arrive through an administrator rather than a self-serve signup and may not be shown the checklist at all.
Follow-up
- Activation rises three points but week-4 retention is flat. What do you tell the team, and what would you need to distinguish a real gain from pulled-forward activity?
- The checklist ships on web only. What changes in the denominator, and what breaks if you leave every surface in?
- Signup mix shifted toward 'invite' the same week. How would you show whether the activation move was mix or behaviour?
Reminder volume where the guardrail opposes the primary metric
The growth team proposes tripling weekly reminder email volume. The north star is weekly active accounts completing a core action, counted on account_id from fct_event (is_core_action, account_id, occurred_at_utc, surface). Its stated guardrail is week-over-week repeat rate together with notification opt-out and unsubscribe rates. Reminders will move the primary up and the guardrail down, by design, and both effects are real. Define the decision rule before the test runs: what magnitudes make this a ship and what makes it a stop. Deliverable: the rule, including the exchange rate you are using between the two quantities.
Approach
- Name the conflict precisely rather than calling it a balance: the reminder buys one week of an account returning and spends permission to contact that account, and permission is not renewable, so the two quantities are not comparable as percentage points.
- Put both sides into one unit before arguing about thresholds. Value the primary gain as incremental core-action weeks over the horizon; value an opt-out as the forgone email-driven active weeks over that account's remaining expected lifetime.
- Read opt-out as a stock, not a flow: accumulate it over the test, because a weekly opt-out rate that looks small is a cumulative curve that only ever rises within a fixed set of contactable accounts.
- Run long enough for the novelty to decay and use the late number in the trade: compare week-1 lift with week-4 lift, state the decay you observed, and refuse to price the decision on a week-1 read.
- Write the outcome as two numbers and a default action, including what happens when the result lands between them — hold and test a smaller volume increment rather than shipping on ambiguity.
Worked solution 30 min
- Measure the starting stock: current opt-out and unsubscribe rate per 1,000 contactable accounts, and the share of weekly active accounts whose session began from referrer_channel = 'email'.
- Estimate the two effects separately over four weeks: incremental weekly active accounts per 1,000 extra sends, and incremental cumulative opt-outs per 1,000 extra sends.
- Convert opt-outs into forgone active weeks: email-driven active weeks per account per year multiplied by remaining expected account lifetime, and set that against the incremental active weeks bought.
- Compare week-1 with week-4 lift, state the decay rate, and carry the week-4 figure into the trade.
- Write the rule as two thresholds plus a default action for the middle case.
Follow-up
- Opt-out is flat but week-over-week repeat rate falls. What is the most likely mechanism, and does it change the decision?
- You do not have a year of data to estimate remaining account lifetime. What do you substitute, and how do you keep the answer honest about that?
- Does randomising on account rather than on user change either the readout or the size of the test?
A conversion rate that fell in one regulatory region
Visit-to-signup conversion fell 1.3 points over six weeks. Signups cut by dim_user.country_code put the fall in one regulatory region where a consent banner shipped in week one, but absolute signups from that region are flat. fct_session carries consent_state, visitor_id, is_bot_flagged and session_date and no country column, so the denominator cannot be cut the same way. Using fct_session and fct_event, decide whether behaviour changed or the denominator did, state what these tables cannot settle, and name the one column that would settle it.
Approach
- Name the asymmetry before computing anything. The numerator is user-keyed and therefore cuttable by country; the denominator is visitor-keyed and is not. Dividing a region-filtered numerator by an unfiltered denominator produces a quantity that is not a rate, and presenting it as a regional conversion rate is the first mistake available here.
- Attack the denominator on the dimension you do have. Compute distinct visitor_id per week and sessions per distinct visitor_id per week: a consent banner that blocks or shortens the identity cookie raises the distinct-visitor count and lowers sessions per visitor, which depresses any visitor-keyed rate with no behaviour behind it.
- Split on consent_state. Sessions with consent_state = 'denied' can enter the denominator but can never be joined forward to a signup, so a rising denied share mechanically drives the pooled rate down by roughly its own share. Report the granted-only rate and the denied share as two separate numbers rather than one blended figure.
- Cross-check with measures that do not depend on the visitor key at all: absolute weekly signups, which are given as flat, and signups per session rather than per visitor.
- State the limit honestly. Without country on the session or on its entry event, the regional attribution rests on the numerator alone, and the correct request is that one column, not a more elaborate model on top of the data you have.
Follow-up
- If granted-only conversion is the metric going forward, what selection bias have you accepted, and in which direction does it point?
- How would you handle the six weeks of already-published history once the new definition is adopted?
- What is the smallest instrumentation change that restores a cuttable denominator without collecting more personal data than before?
For someone who has spent the last year in notebooks, dashboards or modelling work and has not written raw SQL under time pressure. The first four days rebuild query fluency against a fixture you control and can verify by hand; the last three attach that fluency to the rest of the loop.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Build a fixture you can check answers against
- Create a local Postgres or SQLite database with four tables (users, sessions, events, orders) holding roughly 200 rows you generated yourself, so you know the contents well enough to predict every result.
- Deliberately seed the cases that break queries: a user with no sessions, a session with no events, two orders sharing a timestamp, a NULL in one join key, and one duplicated user row.
- Before writing any SQL, hand-compute five answers on paper (how many users placed at least one order, median orders per ordering user, and three others) and save them as the ground truth for the week.
Deliverable: A one-command seed script plus a text file of five hand-computed answers to grade every later query against.
Practice prompt ↗Practice prompt ↗Worked solution ↗02Joins, filters and NULL semantics
- Answer "which users have no orders" three ways (LEFT JOIN with IS NULL, NOT EXISTS, NOT IN) and confirm that the NOT IN version returns zero rows once the subquery contains a NULL, because the comparison is never TRUE.
- Reproduce the LEFT JOIN that silently collapses to an inner join by putting a right-table predicate in WHERE, then fix it by moving the predicate into the ON clause, and record both row counts.
- Create a fan-out bug on purpose by joining orders to order_items and summing the order total, then correct it with a pre-aggregated subquery and explain in one line which table changed the grain.
Deliverable: One annotated .sql file holding the three join traps, each with the wrong result and the corrected result side by side.
Practice prompt ↗Practice prompt ↗03Window functions and frames
- Write three window queries against the fixture: a running order total per user, the rank of each order within its user by value, and the day gap to that user's previous order, then check each against the day-one ground truth.
- Run ROW_NUMBER, RANK and DENSE_RANK over a column containing ties, print all three side by side, and write one sentence on when each is the correct choice.
- Switch one query from the default frame (RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW, which is what you get when ORDER BY is present and no frame is written) to ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW, and explain why the output differs only when the ORDER BY column has duplicates.
Deliverable: Three verified window queries plus a short note explaining the RANGE versus ROWS difference in your own words.
Practice prompt ↗Practice prompt ↗04The four analytical query patterns
- Write a monthly retention grid: first order month per user, then months-since-first as the column, and verify that month zero equals the cohort size exactly.
- Sessionize the events table under a 30-minute inactivity rule using LAG plus a cumulative sum over a new-session flag.
- Build a four-step funnel that counts distinct users rather than events at each step, and state the rule you applied to a user who reaches step three without ever logging step two.
Deliverable: One file with the retention, sessionization and funnel patterns, each carrying a one-line note on the assumption it bakes in.
Practice prompt ↗Practice prompt ↗Worked solution ↗05Write SQL the way you will have to write it live
- Set a 12-minute timer and solve three medium prompts in a plain editor with no execution and no autocomplete, then run them and tally syntax errors separately from logic errors.
- Narrate one solution aloud while writing it, stating the grain of each intermediate result (one row per user, one row per user-day) before you type its body.
- Rewrite your slowest solution as a CTE chain where every CTE name states its grain, and time yourself re-solving it from blank.
Deliverable: A recording of one narrated solution plus an error tally that separates syntax from logic.
Practice prompt ↗Practice prompt ↗06One day for everything that is not SQL
- Write the preconditions of the two-sample t-test from memory, then check them: independent observations, and a difference in means whose sampling distribution is approximately normal, which at large sample sizes follows from the central limit theorem rather than from normality of the raw values.
- Write the difference between an odds ratio from logistic regression and a relative risk, and state the condition under which the two are close (low outcome prevalence).
- Prepare a 90-second answer to "how would you know this model is any good" that names the metric, the baseline you would beat, and the cost of the errors you care about.
Deliverable: One page of notes covering test preconditions, the odds-ratio caveat and the model-quality answer.
Practice prompt ↗07Full loop rehearsal
- Run a 45-minute mock with someone willing to interrupt: 20 minutes of SQL, 15 minutes defining a metric, 10 minutes on a past project.
- Re-solve from blank the two queries you were slowest on this week and compare the times against day five.
- Write a five-line answer to "walk me through a project" that puts a number in the first sentence and names the decision the work changed.
Deliverable: Mock feedback notes plus a timed project narrative you can deliver without reading it.
Practice prompt ↗Worked solution ↗Expand any day for tasks and deliverables. Your progress is saved on this device.
Sometimes the honest read is that the initiative did not work, and the person who commissioned the analysis was hoping otherwise. Interviewers want to know whether you softened it. Prepare the case where you delivered an unwelcome result, how you presented the uncertainty without hiding behind it, and what the team did next.
How do you handle imbalanced datasets in a classification task?
How do you handle imbalanced datasets in a classification task?
Approach
- Quantify the outcome, including what you would not claim credit for.
- Name the disagreement or constraint, and how you resolved it with evidence.
- State the situation in two sentences and spend the rest on your reasoning.
Follow-up
- How did you know the outcome was caused by your change?
- What would you do differently if you ran that project again?
Walk through an analysis you got wrong and what changed
Describe an analysis of yours that turned out to be wrong after somebody had already acted on it. You have four minutes. The account must name the defect mechanically, the join, the filter, the window or the identity key, rather than describing it as a communication problem. It must also say who did what because of the wrong number, how the error surfaced, how long it stood, and what control you put in place so that class of error cannot reach a decision again. Do not pick an error nobody acted on.
Approach
- Recognise what is being probed: whether you can be specific about your own failure without minimising it or performing contrition. The discriminator is whether the defect has a mechanism the listener could reproduce in their own warehouse.
- Choose the case by blast radius rather than by comfort. An error nobody acted on tests nothing, and picking one signals that you are managing the interview instead of answering it.
- Structure the account in six beats: the number, the decision it drove, the defect, the detection, the correction, the control. Keep the defect to one reproducible sentence, for example an inner join to fct_subscription_period that dropped accounts with no subscription row and so computed retention over payers only.
- State the direction of the bias, not only its existence. A filter or join that removes rows usually moves a metric predictably, and knowing which way shows you diagnosed the mechanism rather than patched the symptom.
- Be exact about detection and elapsed time. 'A colleague noticed' and 'the row-count assertion failed before publication' are different answers about the same organisation, and the second one is the one your control is supposed to produce next time.
- End on the control, its cost, whether it has fired since, and one thing it does not cover.
Follow-up
- What did the control cost, and has it fired since? If it never has, how do you know it works?
- How long did the wrong number stand before anyone questioned it, and what does that say about the review path it went through?
- What is the equivalent mistake you are most likely to make in this role, given the tables you would be working in?
Handle a request for numbers supporting a decision already made
A senior leader has already decided to sunset a plan tier and asks you for the analysis showing it is the right call. Accounts on that tier carry 6% of MRR at constant FX and have the highest licensed-seat utilisation in the book. The leader's support matters to your next review cycle, and the decision is being presented in four days. Deliver what you produce, what you decline to produce, and the exact sentence you will say in the meeting where the number appears on a slide.
Approach
- Recognise what is being probed: whether you can find the legitimate request inside an illegitimate framing instead of either complying or refusing on principle. The generic answer promises to push back; the strong one produces something genuinely useful and states its limits in the room, without ambushing anybody.
- Separate the decision from the justification. Sunsetting the tier may be correct for reasons the data does not hold, such as support cost, roadmap surface area or sales motion. What you decline is a one-sided document. What you produce is the case read both ways, which also happens to be more useful to the leader.
- Build the symmetric analysis: MRR at risk at constant FX, the share of affected accounts with a plausible migration path given seats_licensed and billing_term, the recovery rate assumed for that migration and where it came from, and the downside case in which high-utilisation accounts treat the sunset as a reason to re-evaluate the vendor entirely.
- Surface the inconvenient fact privately and early. The highest seat utilisation in the book is a retention signal, and the leader should hold it before the room does, so they can incorporate it rather than be caught by it.
- Agree the meeting sentence in advance with the leader, so that nobody is surprised. Something to the effect that the tier is 6% of MRR and its accounts are the most heavily used in the book, and that the case for sunsetting rests on cost and focus rather than on revenue. That is true, it supports the decision on its real grounds, and it stops the deck claiming the numbers endorse it.
- Decide your own line before you need it: what you will not put your name to, and that the route if asked anyway is your own manager rather than a confrontation in the meeting.
Follow-up
- The deck circulates with your analysis included and the downside case removed. What do you do, and by when?
- What changes if the honest analysis says the sunset is clearly the wrong call?
- How do you write the same memo when the leader is your skip-level and the meeting is tomorrow?
- 01
How do you handle imbalanced datasets in a classification task?
- 02
Describe an analysis of yours that turned out to be wrong after somebody had already acted on it. You have four minutes. The account must name the defect mechanically, the join, the filter, the window or the identity key, rather than describing it as a communication problem. It must also say who did what because of the wrong number, how the error surfaced, how long it stood, and what control you put in place so that class of error cannot reach a decision again. Do not pick an error nobody acted on.
- 03
A senior leader has already decided to sunset a plan tier and asks you for the analysis showing it is the right call. Accounts on that tier carry 6% of MRR at constant FX and have the highest licensed-seat utilisation in the book. The leader's support matters to your next review cycle, and the decision is being presented in four days. Deliver what you produce, what you decline to produce, and the exact sentence you will say in the meeting where the number appears on a slide.
Is this an official Compass interview guide?
No. It is PracHub's own research and practice material for the Data Scientist role at Compass. Rounds and questions reflect what candidates have reported, not a process Compass has published, and they change over time. Confirm the current format and scope with your recruiter.
PracHub interview research ↗How long does the interview process typically take?
The process varies but often involves 4 to 6 rounds. It is not uncommon for the process to take several weeks, so prepare for a sustained engagement.
PracHub interview research ↗What is the best way to prepare for the case study portion?
Focus on structuring your answers. Start with the business goal, identify the data needed, propose a model, and finish by discussing how you would measure success and handle potential pitfalls.
PracHub interview research ↗How difficult are the coding rounds?
The coding rounds are designed to test your ability to solve practical problems rather than complex algorithmic puzzles. Focus on writing clean, readable, and efficient code.
PracHub interview research ↗Does Compass value industry experience over academic research?
Compass values practical application. While academic background is important, demonstrating that you have solved real-world problems and delivered measurable impact is what truly differentiates a candidate.
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.
- 01PracHub interview research ↗
PracHub editorial research into this company and role, maintained with this guide. Candidate-reported, not an employer publication.
PracHub page · Accessed 2026-09-22 - 02PracHub Data Scientist practice ↗
Cross-company practice questions for this role.
PracHub page · Accessed 2026-09-22 - 03PracHub interview preparation framework ↗
The framework the preparation plan follows.
PracHub page · Accessed 2026-09-22
Explore related engineering environments and compare the preparation focus.
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