Seagate · Data Scientist
Updated · 2026-09-24

Seagate Data Scientist
Interview Questions & Guide 2026

THE 60-SECOND BRIEF

As a Data Scientist at Seagate, you are at the intersection of massive-scale data storage technology and advanced analytical intelligence. You play a pivotal role in transforming raw data—generated from manufacturing processes, supply chain logistics, and product performance telemetry—into actionable insights that drive the future of data infrastructure. Your work directly influences how Seagate optimizes its high-capacity storage solutions and maintains its competitive edge in a rapidly evolving market.

Learn the economics of the product category before the loop. Marketplaces, subscription products and ad-supported products turn on different core quantities (match rate and liquidity, retention and churn, fill rate and yield) and fail in different characteristic ways.

Seagate candidates report 5 rounds · ≈ 4-6 weeks. The stages below are what candidates describe, not a published process.

Separate novelty effects from durable behaviour changeDecompose a metric move by segment and mixSize an experiment before anyone launches it

32 min read

Browse Data Scientist questions

See the practice prompts

14Practice promptsAcross five skill areas
3With worked solutionsIncluded in the practice prompts

As a Data Scientist at Seagate, you are at the intersection of massive-scale data storage technology and advanced analytical intelligence. You play a pivotal role in transforming raw data—generated from manufacturing processes, supply chain logistics, and product performance telemetry—into actionable insights that drive the future of data infrastructure. Your work directly influences how Seagate optimizes its high-capacity storage solutions and maintains its competitive edge in a rapidly evolving market.

This role is both technically demanding and strategically significant. You will often work within smaller, focused teams, collaborating closely with product managers and engineers to solve complex, real-world problems. Whether you are improving yield rates in manufacturing or analyzing time-series data to predict hardware reliability, your contributions are tangible and critical to the company's operational success.

01

Initial Screening

reported

A screening call is a matching exercise run by someone who will not evaluate your statistics. They are checking that the work described on your resume is work you personally did, and that its scope matches the level the role is written for. Logistics get settled in the same half hour so nobody spends an interviewer's afternoon on a mismatch. The answer that fails is the one narrated in the plural. If every sentence is 'we built' and 'the team decided', there is nothing specific to write down about you. Name the piece that was yours, the decision you made inside it, and what changed after.

What to demonstrate

  • Whether the ownership implied by your resume survives one round of follow-up about who actually did which part
  • Whether your described scope (data size, stakeholders, what shipped) matches the seniority the role is written at
  • Whether timeline, location and compensation expectations make the rest of the loop worth scheduling

How to prepare

  • Rewrite your top three resume bullets in the first person singular, each with the decision you made and what moved afterwards, then say them out loud once so the 'we' does not return under pressure
  • Attach one number to each project: the baseline, the change, and the window it was measured over. Where impact was never measured, say that plainly rather than inventing a figure
  • Settle your compensation range before the call and give it as a range with a reason behind it, such as current total comp or a competing timeline, instead of deflecting the question twice
PracHub interview research ↗
02

Technical Rounds

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 ↗
03

Conversational Interviews

reported

An added round often puts you in front of someone outside the core hiring team: a partner engineer, a product owner, a domain expert, sometimes a more senior manager. The question they are really asking is not whether you can do the work but whether they would trust a number that came from you. That changes what a good answer looks like. Lead with what the decision cost and what it changed, keep the method available but not central, and be plain about the limits of your evidence. Overstating a result is the fastest way to lose this round.

What to demonstrate

  • Whether you can explain a technical choice to someone who will never read your code, without either flattening it into nothing or hiding inside jargon
  • Honesty about evidence strength: what the analysis establishes, what it only suggests, and what it cannot say at all
  • How you take disagreement, specifically whether you update on a good objection, hold your position with reasons, or fold on contact

How to prepare

  • Write the two-sentence version of your most technical project for a non-specialist, then check that neither sentence needs a method name to make sense.
  • For one result you are proud of, write the strongest objection someone could raise and a response that concedes the part of it that is correct.
  • Prepare one decision that turned out to be wrong: how you found out, what it cost, and what you changed afterwards. A senior cross-functional interviewer asks for this more often than a technical one does.
PracHub interview research ↗
04

Structured Technical Sessions

reported

This round decides whether someone can hand you a schema and a question and trust the number that comes back. Correctness under a clock is the bar, not clever syntax. The habit that separates strong from weak answers is checking the grain: after every join, know how many rows you expect and whether the count moved. Most wrong answers in this format are not wrong logic, they are a fan-out from a key that turned out not to be unique, or a filter applied before an aggregate when it belonged after. Say what you expect before you run it.

What to demonstrate

  • Whether your row counts survive each join, and whether you notice on your own when they do not
  • Deliberate handling of rows that fail to match, including whether the question needs an inner join or a left join with the non-matches kept and counted
  • Whether NULLs are treated on purpose, given that a NULL compares equal to nothing and that COUNT of a column skips it
  • Reaching a defensible answer inside the window instead of a refined one after it

How to prepare

  • Take a two-table schema, write a join that fans out on purpose, then fix it by collapsing the many-side to one row per key before joining. Repeat until the fix is reflex rather than recall.
  • Write a funnel as one query and print the distinct user count at each stage, then confirm each stage is a subset of the one above it rather than assuming it
  • Do a few timed runs in a plain text box with no autocomplete and no formatter, since assessment editors often have neither
PracHub interview research ↗
05

Take-Home Component

reported

The clock is part of the test. Three to six hours is not enough to do everything the dataset supports, so the submission mostly reveals how you spend a fixed budget against an open question. A reviewer sees which paths you took and, by absence, which you abandoned. Work that runs out of time inside the analysis ships a thin conclusion, while work that cuts scope early protects the last hour for writing. The most reliable way to lose here is to leave the scoping decision implicit, so it reads as something you missed rather than something you chose.

What to demonstrate

  • Whether the scope you settled on is presented as a decision with a reason, rather than left for the reader to infer from what is missing
  • Whether the depth of the work is consistent with the stated time budget, instead of several half-finished directions left open
  • Whether the closing section reads as something written on purpose rather than assembled from whichever cells survived

How to prepare

  • Run a timed rehearsal on a public dataset with a hard stop, holding the final sixty minutes for writing no matter where the analysis has got to
  • Before opening the data, list the questions it could plausibly answer, pick one, and keep the discarded ones as a short note on what you did not attempt and why
  • Commit a one-line finding after each analysis step so the writeup is assembled from recorded results rather than from memory at midnight
PracHub interview research ↗

PracHub editorial advice for the preparation topics above.

01

Counting on an identity key that changes underneath the metric

visitor_id is per browser and per device, and it resets on cookie clearance, private browsing and platform privacy changes, so the distinct-visitor count drifts upward for reasons unrelated to reach. Any rate with visitors in the denominator therefore decays over time even when behaviour is constant, and any rate with visitors in the numerator inflates. The stitching at signup makes it worse in both directions: a user who signed up on mobile and returns on desktop is two visitors and one user, while a shared device is one visitor and several users. Decide which key each metric is counted on, write it into the definition, and when comparing a period before and after a platform privacy change, expect a level shift in every visitor-keyed metric and do not attribute it to the product.

02

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.

03

Treating a non-significant result as proof of no effect

Say whether the confidence interval excludes the effect sizes you would have cared about. If it does not, the honest reading is that the test was underpowered, so report the minimum detectable effect the design could have found and what sample size would resolve it.

04

Comparing periods without accounting for seasonality or day-of-week

Compare whole weeks against whole weeks and check whether the same swing appeared in prior cycles or prior years before attributing it to anything you changed. Weekday and weekend populations often differ enough that a Tuesday-to-Saturday comparison is meaningless.

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

11 technical prompts3 include a worked solution

Can you explain the difference between Linear Regression and Logistic …

medium
machine learning and modelling

Can you explain the difference between Linear Regression and Logistic Regression in a business context?

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. Set a baseline first, so any model has something honest to beat.
Follow-up
  • What would you monitor after launch to know the model is still valid?
  • How would you choose the decision threshold, and who owns that choice?

How do you determine when to use PCA (Principal Component Analysis) fo…

medium
machine learning and modelling

How do you determine when to use PCA (Principal Component Analysis) for dimensionality reduction?

Approach
  1. Set a baseline first, so any model has something honest to beat.
  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
  • What would you monitor after launch to know the model is still valid?
  • Where could label leakage enter this setup?

What are the primary differences between RNNs and CNNs, and in what sc…

medium
machine learning and modelling

What are the primary differences between RNNs and CNNs, and in what scenarios would you apply each?

Approach
  1. Frame the prediction: the label, the moment of prediction, and the action it triggers.
  2. Check what information would not exist at prediction time, and exclude it.
  3. Set a baseline first, so any model has something honest to beat.
Follow-up
  • What would you monitor after launch to know the model is still valid?
  • How would you choose the decision threshold, and who owns that choice?

Permutation test for a difference in conversion rates

mediumWorked solution
permutation testresamplinginference

Write a two-sided permutation test from scratch for a difference in conversion rates, using no scipy hypothesis function. Input: a DataFrame with unit_id, variant in {control, treatment} and converted in {0,1}, one row per randomisation unit. Compute the observed difference in proportions, then build the null distribution by reshuffling the variant labels while holding each arm's size fixed. Report the p-value as (1 + the count of permuted statistics at least as extreme in absolute value) / (B + 1) with B at least 10,000, and return the permutation distribution.

Approach
  1. Name the null being tested: the sharp null that each unit's outcome is the same under either label. That is what licenses permuting labels, and it is stronger than the null of equal means, which matters when someone asks whether the test is valid under unequal variances.
  2. Extract converted to a single numpy array of 0s and 1s and record n_treatment. Every permutation is then just a reshuffle of one array, and the treatment mean is the mean of the first n_treatment entries of the shuffled array.
  3. Vectorise the B permutations with rng.permuted on a tiled 2-D array, or with argsort of a (B, n) random matrix. A Python loop calling np.random.shuffle B times is correct but roughly an order of magnitude slower and often runs past the time limit.
  4. Use the +1 correction in both numerator and denominator. Without it a p-value of exactly 0 is reportable, which is false: the observed labelling is itself one of the permutations, so the smallest attainable p-value is 1/(B+1).
  5. Compare the resulting p-value against a two-proportion z-test as a sanity check. At these sample sizes they should agree closely; a large divergence means the statistic or the shuffle is wrong, not that the permutation test found something subtle.
Worked solution 25 min
  1. y = df['converted'].to_numpy(); n_t = (df['variant'] == 'treatment').sum(); obs = y[treat_mask].mean() - y[~treat_mask].mean().
  2. Build the null: for B draws, shuffle y and take the mean of the first n_t entries minus the mean of the rest.
  3. p = (1 + (np.abs(null) >= abs(obs) - 1e-12).sum()) / (B + 1), with the small tolerance so exact ties count as at least as extreme.
  4. Return obs, p and the null array; plot or describe the null to confirm it is centred at 0.
EXPECTED RESULTThe observed difference, a p-value in [1/(B+1), 1], and a null distribution whose mean is approximately 0 and whose standard deviation approximately matches the analytic pooled standard error sqrt(p_pool*(1-p_pool)*(1/n1 + 1/n2)).
Follow-up
  • The arms are 200 and 20,000 units. Does the permutation test stay valid, and what happens to its resolution at B = 10,000?
  • Give a 95 percent confidence interval for the difference. Can you get it from this permutation distribution, and if not, what would you run instead?
  • The randomisation unit is user_id but the outcome is per session. What breaks, and what is the fix?

For a candidate whose interviews will centre on A/B testing, metric movement and causal claims. Design comes before arithmetic, arithmetic before analysis, and the week ends by rehearsing the readout rather than the derivation.

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
01Design one test end to end on paper
  • Take a single feature change and write the full design: randomization unit, the exact point of exposure, the primary metric with its grain, guardrails, allocation, planned duration, and the decision rule committed before any data exists.
  • Write why the randomization unit must sit at or above the level where treatment can spill over, and give one case where user-level randomization is still contaminated (shared accounts or devices, or two participants in the same marketplace).
  • State in advance what you will do if the primary metric is flat while a secondary metric is significant.

Deliverable: A one-page test design with a decision rule written before launch.

Practice prompt ↗Practice prompt ↗Worked solution ↗
02Power arithmetic until it is automatic
  • Compute required sample size per arm for a binary metric with the normal approximation, n is approximately 2 times (z for alpha/2 plus z for power) squared times p(1 minus p) divided by delta squared, for baselines of 2, 10 and 40 percent at a 5 percent relative lift, and note that for a fixed relative lift the requirement falls as the baseline rises because delta grows proportionally with p.
  • Redo the calculation for a continuous metric using variance in place of p(1 minus p), and show why a heavy-tailed quantity such as revenue per user needs either far more traffic or a capped version with a stated cap.
  • Convert one of the results into weeks given a weekly eligible traffic figure, then list the two honest ways to shorten it (accept a larger detectable effect, or reduce variance) and write why quietly lowering the power target is a decision to miss more real wins, not a speedup.

Deliverable: A small script or sheet that maps baseline, minimum detectable effect, alpha and power to sample size and weeks, cross-checked against a published calculator.

Practice prompt ↗Practice prompt ↗
03Variance and the unit-of-analysis problem
  • Take a ratio metric whose denominator is not the randomization unit (clicks per session, randomized by user) and compute the standard error twice, once naively at session level and once by the delta method or a user-level bootstrap, then record how much the naive version understates it.
  • Implement CUPED on simulated data: choose a pre-period covariate X measured before assignment, estimate theta as Cov(Y, X) divided by Var(X), and analyse Y minus theta times (X minus its mean) in place of Y. Confirm the variance of the adjusted outcome equals the raw variance multiplied by one minus the squared correlation between Y and X, so a correlation of 0.45 removes about 20 percent of the variance and not 80.
  • Now run that simulation a few hundred times and confirm the adjusted effect estimate is unbiased for the same effect rather than numerically identical to the raw one. Within any single run the two differ, sometimes by a large fraction of the true effect, because the two arms' pre-period covariate means never coincide exactly in a finite sample; they agree in expectation, which is the property that matters and the one to state out loud.

Deliverable: A notebook showing the adjusted estimator with a measurably smaller variance than the raw one, plus a repeated-simulation table showing the two estimators agreeing on average while differing run by run.

Practice prompt ↗Practice prompt ↗
04Validity threats you can actually test for
  • Run a sample ratio mismatch check as a chi-square goodness-of-fit test against the intended allocation, and write the three causes you would chase first (assignment logged before exposure, an arm-specific redirect or load failure, bot filtering applied asymmetrically).
  • Simulate peeking: generate A/A data, test daily at alpha 0.05 across 14 looks, record the inflated false positive rate, then apply an alpha-spending boundary or commit to a fixed horizon and confirm the rate returns to nominal.
  • Write how you would separate a novelty effect from a durable lift using the treatment effect plotted against days since first exposure, and what shape would change your recommendation.

Deliverable: One table showing the peeking false positive rate before and after correction, plus a written SRM triage list.

Practice prompt ↗Practice prompt ↗Worked solution ↗
05When randomization is not available
  • Write the identifying assumption for difference-in-differences (parallel trends in the absence of treatment), then plot pre-period trends for two candidate control groups and justify rejecting one of them.
  • Design a switchback test for a change where user-level randomization would leak across participants, choosing a time-block length against the carryover you expect and saying how you would detect carryover in the data.
  • List what an interrupted time series or a synthetic control buys you and the one thing neither can rule out: an unobserved shock that coincides with the launch.

Deliverable: A one-page memo recommending a single quasi-experimental design and naming its weakest assumption explicitly.

Practice prompt ↗Practice prompt ↗
06The readout query
  • Write the assignment-to-exposure join that returns exactly one row per unit per experiment, and handle units appearing in both arms by excluding and counting them rather than silently keeping one.
  • Compute the per-arm metric, its variance and the relative lift with a confidence interval in SQL, then reproduce the identical numbers in a notebook as a cross-check.
  • Add a segment breakdown and write the sentence that keeps it from being p-hacking: segments declared in advance, everything else reported as exploratory and corrected for multiplicity.

Deliverable: A single query that outputs the full readout table, matched to a notebook recomputation.

Practice prompt ↗Practice prompt ↗
07Present it to someone who will not read the appendix
  • Give a 10-minute readout of a real or simulated experiment in the order decision, number, uncertainty, caveat.
  • Have your listener ask "can we ship it" in the case where the primary is flat and a guardrail moved, and answer with a recommendation rather than a request for more data.
  • Rewrite your opening line so the recommendation lands before any methodology.

Deliverable: A one-page readout whose first line is the recommendation.

Practice prompt ↗Practice prompt ↗Worked solution ↗

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

Data people depend on systems owned by other teams, and much of the job is negotiating for instrumentation, access, or a fix to a broken pipeline. Prepare an example of getting something changed upstream that you did not control. Describe what you asked for, what you traded, and how you worked while you waited.

How do you handle overfitting in deep learning models?

medium
behavioural and stakeholder questions

How do you handle overfitting in deep learning models?

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. Quantify the outcome, including what you would not claim credit for.
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 missing or inconsistent data in a large dataset?

medium
behavioural and stakeholder questions

How do you handle missing or inconsistent data in a large dataset?

Approach
  1. Pick a story where you drove the decision, not one where you observed it.
  2. Quantify the outcome, including what you would not claim credit for.
  3. Name the disagreement or constraint, and how you resolved it with evidence.
Follow-up
  • What did you decide not to do, and why?
  • How did you know the outcome was caused by your change?

Handle a request for numbers supporting a decision already made

hard
integrityframingstakeholder

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
  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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 overfitting in deep learning models?

  • 02

    How do you handle missing or inconsistent data in a large dataset?

  • 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.

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

No. It is PracHub's own research and practice material for the Data Scientist role at Seagate. Rounds and questions reflect what candidates have reported, not a process Seagate 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 is generally fast-paced, often spanning a few weeks from the initial HR screen to the final decision.

PracHub interview research ↗
Will I be asked to do LeetCode-style coding problems?

While coding is required, the focus is more on data manipulation and SQL rather than complex algorithm puzzles. Be prepared for practical data tasks.

PracHub interview research ↗
What is the culture like at Seagate?

The culture is professional and results-oriented. Teams are often small and highly focused on specific technical challenges, valuing directness and technical expertise.

PracHub interview research ↗
Should I prepare for a technical presentation?

Occasionally, candidates are asked to review a paper or present a project. Be ready to communicate your findings clearly using slides if requested.

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.