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Carbon Lighthouse Data Scientist Interview Questions & Guide 2026

Case practice for Carbon Lighthouse data scientist candidates: scope a vague prompt into a measurable question before you analyze it.

The 60-second brief

The role of a Data Scientist at Carbon Lighthouse is pivotal in leveraging data to drive sustainability and energy efficiency solutions. As a Data Scientist, you will be tasked with analyzing complex datasets to develop actionable insights that influence strategic decisions, enhance product offerings, and ultimately contribute to the company's mission of reducing carbon emissions. You will engage with a variety of data sources, employing statistical methods and machine learning techniques to uncover trends and optimize processes.

Most of the loop measures decision-making under uncertainty rather than recall. You are scored on whether you state your assumptions, commit to an estimate you can defend, and say explicitly what evidence would change it.

Focus areas

  • Set fraud thresholds by expected cost
  • Read vintage curves, not blended portfolio averages
  • Report only matured cohorts for loss metrics

Overview

In this role, you will have the opportunity to work on projects that directly impact energy efficiency programs, contributing to innovative products and services that help commercial buildings operate more sustainably. Your work will enable Carbon Lighthouse to enhance its analytical capabilities, improve operational efficiencies, and deliver significant value to its clients. This position not only demands technical proficiency but also requires a strong understanding of the energy sector and an ability to communicate findings effectively to diverse stakeholders.

The Carbon Lighthouse interview process

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

HR Screening

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

Technical Interviews

Much of what gets scored here happens out loud while you type. Nobody can see your reasoning inside a half-written query, so five silent minutes read as being stuck even when they are not. State the plan in plain language first: which tables, what grain you are aggregating to, and the one filter that defines the population. Then write it. The narration doubles as insurance, because a wrong plan gets caught early and cheaply while a wrong query gets caught at the end with no time left to redo it. A timed statistics section, where one exists, is a separate test with its own clock.

What to demonstrate

  • Whether the query you write matches the plan you just described
  • What you do with a hint, meaning whether the correction gets absorbed or the first approach gets defended
  • Whether you can debug your own wrong output by reading the result set and naming which part of the query produced the anomaly

How to prepare

  • Solve three problems while screen-sharing into a recording, then watch it back and mark every stretch longer than thirty seconds where you said nothing
  • Practise compressing the plan into one sentence before typing, then check afterwards whether the finished query actually matched it
  • Time yourself on statistics questions that carry a business reading, such as what a confidence interval does and does not claim, rather than re-reading notes without a clock

Where candidates lose points

Averaging delinquency across a book that is growing

A loan three months old cannot be 90 days past due, so a portfolio with many recent originations reports a low blended 90+ rate purely from age mix. The blended rate falls fastest exactly when originations grow fastest, which is precisely when credit quality most needs watching, so the metric moves in the reassuring direction during the riskiest period. Only comparisons at equal months on book are valid, which is what a vintage or roll-rate view enforces.

Counting authorizations instead of weighting them, and summing amounts across currencies

Declines skew toward high-value, cross-border and card-not-present transactions, so an unweighted approval rate can sit flat while approved value falls. Merchant retry logic also turns one declined purchase into several rows, inflating the denominator by an amount that varies by merchant and by decline reason. Amounts are held in the minor unit of the transaction currency and that unit is not always two decimals, since some currencies have none and some have three, so summing amount_minor across currencies produces a figure with no interpretation at all.

Ending an analysis without a recommendation or next step

Close with what you would do and what would change your mind, stated as a condition you can check later. If the evidence is genuinely inconclusive, recommend the specific next measurement and say what it costs in time or exposure.

Optimising accuracy on a heavily imbalanced target

State the base rate first, then choose the metric from the relative cost of a false positive against a false negative: precision and recall at the operating threshold, PR-AUC, or expected cost. At a 1 percent positive rate, predicting the majority class for everyone scores 99 percent accuracy and is worthless.

Questions & practice

Describe how you would implement a machine learning model for predicting energy usage.

Medium · machine learning and modelling

Approach

  1. Pick an evaluation metric that matches the cost of each error type, not a default.
  2. Frame the prediction: the label, the moment of prediction, and the action it triggers.
  3. Say how the offline result would be validated online before it is trusted.

Follow-up

  • Where could label leakage enter this setup?
  • How would you choose the decision threshold, and who owns that choice?

Build a vintage delinquency table without pivot or unstack

Easy · vintage analysis · cohorts · groupby · cumulative max

fct_loan_performance_monthly gives loan_id, origination_month, months_on_book, days_past_due, charge_off_flag and restructured_flag. Produce a DataFrame with one row per origination_month and columns for months_on_book 0 through 12, each cell holding the share of that vintage's funded loans that had ever reached 90 or more days past due, or charge-off, by that age. You may not use pivot, pivot_table, crosstab or unstack. Cells for ages a cohort has not yet reached must be NaN rather than zero.

Approach

  1. Define the per-row indicator as days_past_due >= 90 or charge_off_flag, then take a cumulative maximum of it per loan ordered by months_on_book, because the metric is reached-by-age-m, not in-that-state-at-age-m.
  2. Deal with restructuring before the cumulative max. Restructuring resets days_past_due, so a restructured loan re-enters at current and, without the cumulative maximum carrying its pre-restructure worst state, reads as a cure.
  3. Fix the denominator once as the count of distinct loan_id per origination_month across the whole cohort. Prepaid and charged-off loans stop producing rows, so a denominator recomputed at each age silently shrinks exactly where losses land.
  4. Aggregate with groupby(['origination_month','months_on_book'])['ever_90'].sum(), then pre-build the output frame indexed by sorted origination months with integer columns 0 to 12 and assign from the grouped Series by .loc on its index.
  5. Mask cells beyond each cohort's maximum observed months_on_book so an immature cell reads NaN instead of an artificially low rate.

Worked solution (30 min)

  1. Sort by loan_id and months_on_book, build the ever_90 indicator, then apply groupby('loan_id')['ever_90'].cummax().
  2. Compute cohort_size as the distinct loan_id count per origination_month, before any filtering on age.
  3. Group the cumulative indicator by origination_month and months_on_book and sum it to get the numerator per cell.
  4. Create the output frame with the sorted origination months as index and range(0, 13) as columns, fill it from the grouped Series, and divide each row by its cohort_size.
  5. Compute each cohort's maximum observed months_on_book and set every cell to the right of it to NaN.

Expected result: A DataFrame with one row per origination_month and columns 0 to 12, values non-decreasing left to right within every row, near zero in column 0, and NaN forming an upper-right triangle where cohorts have not yet aged.

Verify it yourself

  • Every row is non-decreasing across columns; a decrease means the cumulative maximum was not applied or a restructure reset leaked through.
  • The denominator per row equals the cohort's distinct loan count and does not change across columns.
  • Column 0 is at or near zero for every vintage, since a loan cannot be 90 days past due at its first month end.
  • origination_month plus months_on_book is constant along an anti-diagonal, so one anti-diagonal should reproduce a direct calendar-month filter.

Follow-up

  • Two adjacent vintages diverge at months_on_book 6. How would you separate seasoning, mix shift and a genuine credit-quality change?
  • The three most recent vintages look best on this table. What do you check before saying so?
  • How does the table change if charge-off policy moved from 180 to 120 days past due partway through the series?

Bootstrap a fraud loss rate that clusters within merchant

Medium · bootstrap · clustered resampling · heavy tails

You have a per-transaction frame with auth_id, merchant_id, settled_amount_reporting and net_loss_reporting, both already in one reporting currency. Most rows carry zero loss, a few carry large ones, and losses cluster within merchant. Using only numpy's random generator and no resampling helper from any library, write a bootstrap that returns a 95 percent interval for net fraud loss in basis points of settled volume, resampling merchants with replacement and taking all rows belonging to each drawn merchant. Also produce the naive row-level interval and state which you would report.

Approach

  1. State the estimator before writing it: total net loss divided by total settled volume, times 10,000. It is a ratio of sums, so each replicate recomputes both sums. Averaging per-transaction loss rates instead would weight a five-unit transaction like a five-thousand-unit one.
  2. Pre-aggregate loss and volume to merchant level once. For a ratio of sums, drawing merchants and taking all their rows is arithmetically identical to drawing merchant-level (loss_sum, volume_sum) pairs, so a replicate becomes one integer draw plus two vectorised sums rather than a groupby inside the loop.
  3. Draw B replicates of M merchant indices with replacement, where M is the observed merchant count, compute the ratio per replicate, and take the 2.5th and 97.5th percentiles. Say explicitly that this is a percentile interval and that BCa would correct the skew-induced bias if the decision is close.
  4. Repeat with independent row draws for the naive interval and compare widths on the same replicate count.
  5. Report the clustered interval. Rows within a merchant share an acceptance profile, a category code and a fraud exposure, so they are not independent, and the row-level interval understates variance by roughly the design effect.

Follow-up

  • Your clustered interval is three times wider. How do you explain that to someone who wanted a tighter number?
  • One merchant accounts for 40 percent of losses. What does that do to the interval, and what would you do about it?
  • How does this change if the question is whether two months differ rather than what this month's rate is?

Count-weighted and dollar-weighted approval rates on one currency

Easy · aggregation · denominators · minor units

Using fct_payment_authorization, report the trailing 7-day authorization approval rate two ways for transaction_currency = 'EUR': count-weighted, and dollar-weighted on amount_minor. Exclude is_reversal = true, exclude incremental authorizations (parent_auth_id not null), and exclude zero-amount account verifications. auth_result = 'approved' is the numerator; the four declined_* values make up the rest of the denominator. Return channel, attempts, approved_attempts, approval_rate_count and approval_rate_value. State every exclusion and its reason before you write the SELECT.

Approach

  1. Say the denominator out loud first: attempts on a single transaction currency, excluding reversals, incremental authorizations and zero-amount verifications, because none of those is a purchase attempt a merchant is trying to get approved.
  2. Filter requested_at against a half-open interval (>= start AND < end) so the boundary day is neither dropped nor double counted.
  3. Compute both rates in one pass with FILTER clauses: COUNT() FILTER (WHERE auth_result = 'approved') over COUNT(), and SUM(amount_minor) FILTER (WHERE auth_result = 'approved') over SUM(amount_minor).
  4. Cast one side of each ratio to numeric before dividing, since amount_minor and the counts are integers and integer division silently truncates to zero.
  5. Group by channel and sort by the value-weighted rate, then read the gap between the two rates as a statement about where the declines sit rather than as noise.

Worked solution (20 min)

  1. Write the exclusion list as comments above the query: is_reversal = false, parent_auth_id is null, amount_minor > 0, transaction_currency = 'EUR'.
  2. Build a single aggregate query over fct_payment_authorization with a half-open requested_at predicate and those four filters.
  3. Emit attempts, approved_attempts, approval_rate_count and approval_rate_value with FILTER clauses and a numeric cast on the numerator.
  4. Group by channel, order by approval_rate_value ascending so the worst channel is on top.

Expected result: One row per channel present in the window, with attempts and approved_attempts as integers and both rates as numerics strictly between 0 and 1. approval_rate_value is typically lower than approval_rate_count on ecommerce and moto, because declines concentrate in higher-value card-not-present traffic.

Verify it yourself

  • SUM(attempts) across channels equals a separate COUNT(*) run with the same four filters and no GROUP BY.
  • Dropping the amount_minor > 0 filter raises attempts and moves approval_rate_count while leaving approval_rate_value unchanged, which confirms the zero-amount rows were only ever affecting the count-weighted figure.
  • Both rates are strictly less than 1 unless a channel had no declines at all in the window.

Follow-up

  • The two rates diverge by four points on the ecommerce channel but agree on card_present. What does that tell you, and what would you cut next?
  • How would you extend this to all currencies without summing amount_minor across them?
  • Which of the four decline reasons belong in the denominator of a rate you would put in front of a risk team, and which are really the network's problem?

Accident-quarter loss ratio on earned rather than written premium

Hard · loss ratio · earned vs written · development age

From fct_policy_period_monthly, compute the accident-quarter loss ratio by product_line: incurred losses, being paid_loss_minor plus case_reserve_minor plus ibnr_reserve_minor, over earned_premium_minor for the same accident quarter. State explicitly whether loss_adjustment_expense_minor is included and apply that choice consistently. Also output the same ratio computed on written_premium_minor so the two can be compared. The table holds current values with no valuation-date snapshot. Say in one line which comparison this schema cannot support and what you would need to support it.

Approach

  1. Derive the accident quarter from as_of_month with date_trunc, and note that the table already attributes losses to the month of the loss event while earning premium pro rata into the same month, which is what makes the two sides comparable at all.
  2. Aggregate earned_premium_minor, written_premium_minor and the three loss components to product_line and accident quarter in one pass, keeping loss adjustment expense as its own column so the inclusion choice is a final-select decision rather than something buried in a CTE.
  3. Compute both ratios side by side and a third column for their difference, because the size and sign of that difference is a direct read on whether the book grew or shrank in the quarter.
  4. State the limitation plainly: every row carries today's reserve estimate, so each accident quarter is observed at a different development age and a cross-quarter comparison mixes development with underwriting. A fixed development age needs a valuation-date dimension, that is one row per accident period per valuation, which this table does not have.
  5. Guard against the mirror-image error on the numerator by confirming ibnr_reserve_minor is non-zero on recent quarters; if it is null or zero there, the recent periods are understated twice over and the series is not usable.

Follow-up

  • Written premium exceeds earned premium by 18 percent this quarter and by 3 percent two years ago. What happened to the book, and what does it do to each ratio?
  • How would you build a development triangle from a valuation-dated version of this table, and what would you use the chain-ladder factors for?
  • Statutory presentation conventionally takes the expense ratio on written premium while the loss ratio uses earned. How do you avoid a combined ratio that quietly mixes the two bases?

How would you approach optimizing an energy efficiency program for a commercial building?

Medium · product sense and metrics

Approach

  1. Restate the decision this analysis has to support, and who acts on the answer.
  2. Name one primary metric, then the guardrail that stops it being gamed.
  3. State what result would change your recommendation, so the answer is falsifiable.

Follow-up

  • How would you detect that the metric is being gamed rather than genuinely improving?
  • Which segment would you cut first, and what would that rule out?

Given a dataset on energy consumption, how would you identify trends and anomalies?

Medium · product sense and metrics

Approach

  1. Decompose the metric into the rates that drive it, and say which one you would check first.
  2. Restate the decision this analysis has to support, and who acts on the answer.
  3. Fix the population and the time window before naming any metric.

Follow-up

  • How would you detect that the metric is being gamed rather than genuinely improving?
  • Which segment would you cut first, and what would that rule out?

How would you evaluate the effectiveness of a new energy efficiency program using data?

Medium

Approach

  1. Work from the decision backwards to the evidence you would need.
  2. State your assumptions explicitly before working the problem.
  3. Clarify what is being asked and what a complete answer would contain.

Follow-up

  • How would you know your answer was wrong?
  • What assumption would you test first?

What statistical methods do you find most useful in your analyses?

Medium

Approach

  1. State your assumptions explicitly before working the problem.
  2. Say what you would check first and why it is the highest-information step.
  3. Work from the decision backwards to the evidence you would need.

Follow-up

  • How would you know your answer was wrong?
  • What assumption would you test first?

Success metrics for loosening a fraud decline threshold

Medium · cost asymmetry · guardrails · cohort maturity

A risk team proposes lowering the risk_score cutoff that produces auth_result = 'declined_risk_rule'. Settled volume per active customer is the north star; net fraud loss in basis points of settled volume is the guardrail. The two move in opposite directions by construction. Specify the readout: primary metric, guardrail, the maturity window each is read at, and the decision rule agreed before launch. Show the expected-cost arithmetic that sets the cutoff using an average ticket of 200 units, a 1.5 percent contribution margin, 35 percent recovery on fraud losses, and 12 units of downstream value lost per false decline.

Approach

  1. Refuse the two-metric framing and convert both sides into one currency. Approving a fraudulent transaction costs the amount net of recovery; declining a good one costs the forgone margin plus the downstream value of the customer's reaction. Decline when p times C_FN exceeds (1 minus p) times C_FP, so the break-even probability is p* = C_FP / (C_FP + C_FN).
  2. Put the numbers in. C_FN = 200 times (1 minus 0.35) = 130, C_FP = 200 times 0.015 plus 12 = 15, so p* = 15 / 145 = 10.3 percent. Then show the threshold is amount-dependent: at a 2,000 ticket C_FN = 1,300 and C_FP = 42, giving p* = 3.1 percent, so a single global cutoff is already the wrong shape before any tuning starts.
  3. State the precondition that makes this arithmetic legal: risk_score has to be calibrated, so that a score of 0.10 corresponds to an observed 10 percent fraud rate. A score that only ranks makes p* meaningless. Check the reliability curve before quoting any cutoff to anyone.
  4. Set the maturity windows separately. Volume is readable within days, fraud loss is not, so the guardrail is read only on transaction months with at least 120 days of dispute maturity and the decision stays open until then, or a leading indicator is agreed in advance with its bias written down.
  5. Agree the stopping rule before launch in the right units: revert if matured net fraud loss per unit of incremental settled volume exceeds the figure implied by p*. Fraud loss is supposed to rise when the cutoff loosens, so a rule that triggers on any rise is a rule that was never going to allow the change.
  6. Report the swap set rather than portfolio totals: the transactions the new cutoff approves that the old one declined, and their realised loss rate. Portfolio aggregates dilute the change into invisibility.

Worked solution (30 min)

  1. Compute p* at ticket sizes of 50, 200 and 2,000 with the given margin, recovery and false-decline cost, and tabulate them.
  2. Bucket historical declined_risk_rule authorizations by risk_score decile and, for each bucket, write down what outcome data exists and what does not.
  3. Write the readout spec: primary metric, guardrail, the 120-day maturity rule, the swap-set table and the numeric stopping rule.
  4. Write the calibration precondition in two sentences and say how you would test it.

Expected result: A threshold table giving p* = 28.2 percent at a 50 ticket, 10.3 percent at 200 and 3.1 percent at 2,000, plus a readout spec whose guardrail is explicitly unreadable for 120 days and whose stopping rule is expressed as loss per incremental unit of settled volume rather than as a loss level.

Verify it yourself

  • p* falls as ticket size rises, because fraud loss scales with the amount while the false-decline cost is mostly a fixed relationship term.
  • Setting C_FP equal to C_FN returns p* = 0.5. If your formula does not, the numerator and denominator are the wrong way round.
  • The declined population carries no fraud labels, so any realised fraud rate quoted for the region below the old cutoff has to come from a randomised approval sample rather than from the historical table.

Follow-up

  • Fraud loss in basis points falls after launch. Name two ways that happens without any improvement in decisioning.
  • How do you keep observing outcomes in the region the rule still declines?
  • What changes if the 12 units of downstream value is a guess with no evidence behind it?

Trailing thirty day volume per customer drops week over week

Hard · seasonality · day of week · window alignment

The trailing 30-day settled volume per active customer is down 7 percent against the same metric seven days earlier. Nothing shipped. You have fct_payment_authorization with requested_at, channel, captured_at, captured_amount_minor, settled_at, settlement_amount_minor, plus dim_customer with is_current, kyc_status, onboarded_at and closed_at for the active denominator. Before anyone writes a retention narrative, decide how much of the 7 percent is calendar structure, and hand back a calendar-robust version of the comparison.

Approach

  1. Do the window arithmetic first. Thirty days is four whole weeks plus two days, so exactly two weekdays appear five times and the other five appear four times. Sliding the window by seven days changes which two, and card-present and card-not-present volumes differ sharply by weekday.
  2. Rebuild on a 28-day window, which contains exactly four of every weekday, and see how much of the 7 percent survives. That single change removes the weekday composition effect with no modelling and no assumptions.
  3. Count the structural events inside each window: public holidays, and the billing anchor days that recurring authorizations cluster on. A window holding one fewer month boundary loses a block of recurring volume that has nothing to do with customer behaviour.
  4. Decompose by channel, since recurring, card_present and ecommerce have different calendar signatures. A drop concentrated in recurring points at anchor-day placement; one spread evenly across channels does not.
  5. Compare year over year at a 364-day lag rather than 365, which preserves weekday alignment, and only then read the residual.
  6. Check the denominator on its own. Active customer counts on a trailing window carry their own calendar structure, and a ratio can move because either side moved.

Follow-up

  • Which window goes on the executive dashboard, and what do you give up by choosing it?
  • How would you handle a holiday that moves between years, so that a 364-day lag still misaligns it?
  • If a genuine 2 percent residual survives, what is the smallest cut that tells you whether it is breadth or depth?

Suggested practice checklist

For someone who can already write the query and train the model but stalls when asked what to measure or whether a change is worth making. Metric definition and case structure come first; the technical work is kept as maintenance rather than the centre of the week.

Day 1 — Metric anatomy

  • For three products you use daily, write one primary metric, two input metrics that plausibly move it, and one guardrail that would catch a cheap way of moving the primary at the cost of the product.
  • For one of them, specify the metric precisely enough that two analysts would return the same number: numerator, denominator, unit of observation, time window, and how returning and deleted accounts are treated.
  • Pick a ratio metric and write what happens to it when the denominator shrinks for reasons unrelated to the numerator, with a concrete example of that happening.

Deliverable: A one-page metric tree for one product, with the primary metric written as an unambiguous spec.

Day 2 — Diagnosing a drop without guessing

  • Take the prompt "weekly active users fell 8 percent week over week" and write the segmentation plan before proposing any cause: platform, region, tenure cohort, acquisition channel, and whether the movement sits in the numerator or in a changed denominator.
  • List the instrumentation failures that manufacture fake drops (a client release that stopped firing an event, a bot filter change, a shifted date boundary or timezone) and write the query that rules out each one.
  • Rehearse stating the boring explanations first, seasonality and day-of-week composition, before reaching for a product cause.

Deliverable: A drop-diagnosis checklist short enough to recite from memory in under a minute.

Day 3 — Should we build it

  • Take a feature idea and write it as a bet: what you believe is true, what would have to be true for it to pay off, the metric that would confirm it, and the effect size that would justify the engineering cost.
  • Size the opportunity top-down and bottom-up, then reconcile the two numbers in writing instead of quoting whichever is friendlier.
  • Write the counter-metric that would make you kill the feature even if it wins on the primary metric.

Deliverable: A one-page product memo ending in a decision rather than a list of considerations.

Day 4 — The places aggregate numbers lie

  • Construct a Simpson's paradox numerically: two segments where the treatment wins within each segment yet loses overall, and identify the shift in segment weights that causes it.
  • Take a heavy right-tailed quantity such as revenue per user and write why the mean is the wrong summary, which percentile you would report instead, and what a moving mean with a stable median tells you.
  • Write your definition of a session for the product from day one, then name two real behaviours it misclassifies.

Deliverable: One page holding a worked Simpson's paradox table and a session definition with its two known failure cases.

Day 5 — Technical maintenance, aimed at metrics

  • Solve four timed SQL prompts that all end in a ratio metric, so the question of grain stays live in every answer.
  • Compute a 95 percent confidence interval for a proportion on a small sample, and state why the normal approximation is unreliable when either np or n(1 minus p) falls below roughly 10, along with which interval you would use instead.
  • Take one metric from your day-one tree, write the query that computes it correctly, then write the query that computes it wrong in the most plausible way and explain how you would notice.

Deliverable: Four solved prompts plus a matched correct and plausible-wrong query for one metric.

Day 6 — Turning engineering work into data science stories

  • Write three project stories as situation, decision, trade-off, outcome, each carrying one number and one thing you got wrong.
  • For the story you will lead with, prepare an answer to "what would you do differently" that names a decision you made, not a constraint you were handed.
  • Practise the sentence that reframes a systems project as a question project: the question the work answered, ahead of the pipeline it shipped.

Deliverable: Three written stories with the lead story delivered aloud and timed under four minutes.

Day 7 — Mock case and gap list

  • Run a 40-minute mock case with someone playing a product manager who pushes back on your metric choice, and record it.
  • Listen back and mark every moment you proposed a solution before the success metric existed.
  • Rewrite those moments as the question you should have asked, and rehearse the first 90 seconds of the case until scoping comes before solving.

Deliverable: A recorded case plus a rewritten opening 90 seconds.

Bring numbers, including the ones you are unsure of

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.

What motivates you to work in the field of data science and energy efficiency?

Medium · behavioural and stakeholder questions

Approach

  1. State the situation in two sentences and spend the rest on your reasoning.
  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 would you do differently if you ran that project again?
  • How did you know the outcome was caused by your change?

How do you handle conflicts within your team?

Medium · behavioural and stakeholder questions

Approach

  1. Quantify the outcome, including what you would not claim credit for.
  2. State the situation in two sentences and spend the rest on your reasoning.
  3. Pick a story where you drove the decision, not one where you observed it.

Follow-up

  • What would you do differently if you ran that project again?
  • How did you know the outcome was caused by your change?

Can you provide an example of how you have contributed to fostering an inclusive work environment?

Medium · behavioural and stakeholder questions

Approach

  1. Quantify the outcome, including what you would not claim credit for.
  2. State the situation in two sentences and spend the rest on your reasoning.
  3. Pick a story where you drove the decision, not one where you observed it.

Follow-up

  • What would you do differently if you ran that project again?
  • How did you know the outcome was caused by your change?