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Underdog Fantasy Data Scientist Interview Questions & Guide 2026

Causal inference drills for Underdog Fantasy data scientist prep: diff-in-diff, matching, instruments, and the limits of observed data.

The 60-second brief

As a Data Scientist at Underdog Fantasy, you play a pivotal role in harnessing data to drive decision-making and enhance user experiences. This position is essential to our mission of providing innovative fantasy sports solutions by leveraging statistical analysis, machine learning, and data visualization. Your work will directly influence product features, optimize user engagement, and improve our overall business strategy, ensuring that Underdog Fantasy remains competitive in the rapidly evolving landscape of sports gaming.

How much statistics you need depends on the flavour of the seat. Experiment-facing work wants you deep enough to notice that repeated looks at accumulating data inflate the false positive rate of a fixed-sample test; modelling-facing work wants estimation and honest uncertainty intervals.

Focus areas

  • Turn a vague request into a measurable question
  • Size an experiment before anyone launches it
  • Decompose a metric move by segment and mix

Overview

Data scientists at Underdog Fantasy tackle complex challenges, such as predicting user behavior, analyzing game performance metrics, and developing models that enhance our game offerings. You will collaborate closely with product managers and engineers, utilizing your expertise to inform the development of features that delight our users. The role is not only about data analysis; it involves strategic thinking and the ability to communicate insights effectively to drive results across teams.

Candidates can expect to engage with a variety of data sources and methodologies, from traditional statistical techniques to cutting-edge machine learning frameworks. This dynamic environment offers opportunities for professional growth, as you help shape the future of fantasy sports through data-driven insights.

The Underdog Fantasy interview process

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

Recruiter Screen

Data Scientist covers at least four different jobs: experimentation, product analytics, causal work on observational data, and applied modelling that ships into a system. A screening call is the cheapest place to find out which of them is being hired for, and doing that diagnosis openly reads as senior rather than fussy. Ask what the last few pieces of work on the team actually were, and roughly how a week splits between querying, modelling and stakeholder time. Then say which parts of that you have done and which you have not. Claiming the whole range is the fastest way to be caught one round later.

What to demonstrate

  • Whether you can distinguish the flavours of the role and locate your own experience inside one of them honestly
  • Whether you name what you have not done instead of stretching to cover every line of the posting
  • Whether your hard constraints (notice period, location, work authorisation, level) surface now rather than at offer stage

How to prepare

  • Map the last two years of your time into rough percentages across query writing, experiment design, modelling and stakeholder work, so a question about scope has a real answer
  • Mark every responsibility in the posting as done, adjacent or new, and prepare one sentence for each adjacent item naming the closest thing you have actually built
  • Decide which logistics are non-negotiable before the call so you can state them in one sentence rather than negotiating live

Technical Interviews

Before anything else, this round is a reading test. You are given a small schema and a question phrased in business language, and most of the difficulty sits in the gap between them. Who counts as an active user, does a refunded order still count as an order, is that date column an event time or a load time. Weak answers start typing immediately and compute something precise about the wrong population. Strong ones pin the definition in one sentence, name the column that encodes it, then write the query. On a timed assessment with nobody to tell, write the definition in a comment anyway.

What to demonstrate

  • Whether an ambiguous term becomes a specific column and filter before any computation happens
  • Whether you read the schema for keys and cardinality rather than only for column names
  • Whether the result answers the question at the grain it was asked at, per user or per session or per day

How to prepare

  • Take three metrics you already use and write down the exact filter and exact grain behind each, then practise stating one of them in a single sentence out loud
  • On a schema you have never seen, spend the first minute writing what one row of each table means and which key it is unique on, then predict which joins can duplicate rows
  • Rehearse a version where the definition changes halfway through, and edit the query you have instead of starting over

Where candidates lose points

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.

Treating last-touch attribution as the causal value of a channel

The attribution label on dim_user is the output of a rule that assigns full credit to whichever touch happened to be recorded last inside a lookback window, and that rule systematically rewards channels that sit close to the conversion, especially branded search and retargeting, which largely intercept demand that already existed. Reallocating spend on those labels moves budget toward the channels that are best at being last, which is why attributed return on ad spend often improves while total signups do not. Nothing in the touchpoint data can settle this, because the counterfactual of not running the channel was never observed. The credible reads are a geo holdout or a scheduled pause, sized in advance on the total-signups metric rather than on the attributed one, and the honest framing in the meantime is that the label describes correlation with conversion and not incremental contribution.

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.

Over-explaining the method and under-explaining the implication

Lead with the answer and what you would do about it, then give the approach when asked. Roughly one sentence of method per three of implication is the right ratio for a stakeholder-facing answer; the interviewer already knows what a regression is.

Questions & practice

Write a function to compute the mean and standard deviation of a list of numbers.

Medium · statistics and probability

Approach

  1. Translate the result into the decision it informs, in one plain sentence.
  2. Write down the assumption the method needs before you use the method.
  3. Sanity-check the answer against a simple bound or a simulated case.

Follow-up

  • Which assumption here is most likely to be violated in practice?
  • How would you explain this result to someone who does not know statistics?

Can you demonstrate how to implement a decision tree from scratch?

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?

Describe a project where you utilized machine learning. What challenges did you face?

Medium · machine learning and modelling

Approach

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

Follow-up

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

Cluster bootstrap for a per-session rate randomised on users

Hard · cluster bootstrap · randomisation unit · variance

An experiment randomised on user_id reports a per-session conversion rate, so sessions inside a user are correlated. Input: one row per session with user_id, variant in {control, treatment} and converted in {0,1}. Write a cluster bootstrap from scratch: resample users with replacement within each arm, keep every session of a drawn user, recompute each arm's ratio of converted sessions to sessions, and take the difference. Return the point estimate, a 95 percent percentile interval from at least 2,000 resamples, the naive session-level interval that ignores clustering, and the ratio of their widths.

Approach

  1. Name the estimand precisely: it is a ratio of sums, sum(converted) over sum(sessions) within an arm, not the mean of per-user rates. Those differ whenever session counts vary across users, and the ratio is what the reported metric is.
  2. Resample the cluster, not the row. Draw n_users user ids with replacement inside each arm and take every session belonging to each draw, including duplicate draws of the same user. Keeping the user count fixed per arm rather than the session count is what preserves the sampling design.
  3. Precompute per-user (converted_sum, session_count) once, so each resample is two vector lookups and a division rather than a repeated filter over the session frame. That turns 2,000 resamples from minutes into under a second.
  4. Take the 2.5th and 97.5th percentiles of the 2,000 differences for the interval, and report the point estimate from the full data rather than from the bootstrap mean, since the bootstrap mean carries the resampling bias.
  5. Compute the naive interval from the session-level binomial standard error and compare widths. The expected inflation is roughly sqrt(1 + (m-1)*rho), with m the mean sessions per user and rho the intraclass correlation of converted within users, so a computed ratio far from that value points at a bug in one of the two intervals.

Worked solution (35 min)

  1. per_user = df.groupby(['variant','user_id'])['converted'].agg(['sum','size']); split into two arrays per arm.
  2. point = (t_sum.sum() / t_n.sum()) - (c_sum.sum() / c_n.sum()).
  3. For b in range(B): idx = rng.integers(0, len(t_sum), len(t_sum)); ratio_t = t_sum[idx].sum() / t_n[idx].sum(); same for control; store the difference. Vectorise by drawing a (B, n) index matrix if memory allows.
  4. ci = np.percentile(diffs, [2.5, 97.5]); naive_se = sqrt(p_t*(1-p_t)/n_sessions_t + p_c*(1-p_c)/n_sessions_c); naive_ci = point +/- 1.96*naive_se.
  5. width_ratio = (ci[1]-ci[0]) / (naive_ci[1]-naive_ci[0]).

Expected result: A point estimate identical to the full-data ratio difference, a percentile interval containing that point estimate, and a width ratio greater than 1 whose value approximates sqrt(1 + (m-1)*rho) for the data's mean cluster size m and intraclass correlation rho. A ratio of approximately 1.0 means sessions were resampled instead of users.

Verify it yourself

  • Construct data where every user has exactly one session: the cluster and naive intervals then agree to within Monte Carlo error, since m = 1 makes the design effect 1.
  • Construct data where converted is constant within each user: rho is 1, and the width ratio should approach sqrt(m).
  • The bootstrap distribution's mean sits close to the point estimate; a large offset means the resampled arms have drifted in size.
  • Doubling B narrows the Monte Carlo noise in the percentile endpoints without shifting the interval's centre.

Follow-up

  • Users average 3.4 sessions and the intraclass correlation is 0.12. What width ratio do you predict before running it, and does your bootstrap land there?
  • Give the delta-method standard error for this ratio and say when you would prefer it to the bootstrap.
  • Half the users in the treatment arm have exactly one session. What does that do to the cluster bootstrap's coverage, and how would you check it?

What data structures would you choose for a project that requires fast data retrieval?

Medium · sql and data manipulation

Approach

  1. Check whether any join is one-to-many before aggregating, or the sums inflate.
  2. Compute rates by summing numerator and denominator separately, never by averaging rates.
  3. Say which table is the grain you start from, and join outward from it.

Follow-up

  • How does the query change if the join becomes one-to-many?
  • How would you verify this result without re-running the same query?

Find reactivation gaps in account paid-period history

Hard · gaps-and-islands · window-functions · subscriptions

fct_subscription_period holds account_id, subscription_id, period_start_utc, period_end_utc, period_status and change_reason. A mid-period plan or seat change closes one row and opens another, so a single continuous paid tenure is often many rows, and an account may hold two overlapping subscriptions. Collapse rows with period_status in ('active','past_due') into continuous tenures per account, treating gaps of three days or less as continuous. Return account_id, tenure_start, tenure_end, and for every tenure after the first, the gap in days that preceded it.

Approach

  1. Filter to paid rows only: period_status IN ('active','past_due'). Trialing periods are not tenure, and including them turns every trial that never converted into a one-period tenure followed by a fake churn.
  2. Order by period_start_utc and take a running maximum of all prior ends: MAX(period_end_utc) OVER (PARTITION BY account_id ORDER BY period_start_utc, period_end_utc, subscription_id ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING). Those three columns are the only stable ordering this schema exposes, so check first that they are unique within an account; if rows tie on all three, the island numbering is order-dependent between runs and you need a real row key before the result is reproducible.
  3. LAG on its own is wrong here because with overlapping or nested periods the immediately preceding row by start date is not the one that ends latest, so the running maximum is the part that cannot be shortcut.
  4. Flag a new island when prior_max_end IS NULL OR period_start_utc > prior_max_end + interval '3 days', then number islands with a running SUM of the flag over the same ordering and an explicit ROWS frame.
  5. Group to (account_id, island) taking MIN(period_start_utc) and MAX(period_end_utc), then LAG(tenure_end) OVER (PARTITION BY account_id ORDER BY tenure_start) to compute the preceding gap in days for every tenure after the first.
  6. Sanity-check with change_reason, which is the only lineage this schema carries: list its distinct values first, then confirm that rows recording a plan or seat change sit inside a tenure rather than opening one, and that every tenure after the first opens on a row whose reason records a restart rather than an ordinary renewal. Do not reconcile against a churn timestamp on dim_account, which this schema does not define; and where such a column does exist, a cancellation timestamp records when the request was made and routinely sits weeks before the period it ends.

Worked solution (35 min)

  1. Find an account with a known mid-period upgrade and dump its period rows to use as the trace case.
  2. Check that (period_start_utc, period_end_utc, subscription_id) is unique per account, since the whole ordering rests on it.
  3. Write the paid-rows CTE and the running MAX with the explicit frame.
  4. Add the island flag and the running SUM, then verify the trace account yields one island.
  5. Group to tenures and add the LAG-based gap in days.
  6. List the distinct change_reason values, then count accounts with more than one tenure and compare against the count of accounts carrying a restart-flavoured reason anywhere in their history.

Expected result: One row per (account_id, tenure). An account with a continuous history returns a single row with a NULL preceding gap. Every non-first tenure has gap_days strictly greater than 3 by construction.

Verify it yourself

  • No two tenures for the same account overlap or touch within the grace window.
  • MIN(tenure_start) per account equals MIN(period_start_utc) per account in the filtered input.
  • The account with a known mid-period upgrade produces one tenure, not two.
  • (period_start_utc, period_end_utc, subscription_id) has no duplicates within an account; if it does, say how many accounts are affected before reading the output.
  • The share of accounts with more than one tenure is small; if it is most accounts, the status filter or the grace window is wrong.

Follow-up

  • Why three days of grace? What do 0 and 30 days each do to the count of accounts classed as reactivated?
  • An account runs two concurrent subscriptions for different teams. One tenure or two, and what does the revenue reader expect?
  • How would you turn these tenures into a monthly gross logo churn series without double-counting an account that churned and returned in the same month?

What steps would you take to validate the effectiveness of a new feature based on user data?

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. Name one primary metric, then the guardrail that stops it being gamed.
  3. Restate the decision this analysis has to support, and who acts on the answer.

Follow-up

  • Which segment would you cut first, and what would that rule out?
  • What would you do if the primary metric and the guardrail moved in opposite directions?

How would you approach predicting user churn for our platform?

Medium · product sense and metrics

Approach

  1. State what result would change your recommendation, so the answer is falsifiable.
  2. Decompose the metric into the rates that drive it, and say which one you would check first.
  3. Restate the decision this analysis has to support, and who acts on the answer.

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 of game results, how would you identify factors that lead to user engagement?

Medium · product sense and metrics

Approach

  1. State what result would change your recommendation, so the answer is falsifiable.
  2. Decompose the metric into the rates that drive it, and say which one you would check first.
  3. Fix the population and the time window before naming any metric.

Follow-up

  • Which segment would you cut first, and what would that rule out?
  • What would you do if the primary metric and the guardrail moved in opposite directions?

How do you prioritize tasks when managing multiple projects?

Medium · product sense and metrics

Approach

  1. Name one primary metric, then the guardrail that stops it being gamed.
  2. Restate the decision this analysis has to support, and who acts on the answer.
  3. Decompose the metric into the rates that drive it, and say which one you would check first.

Follow-up

  • Which segment would you cut first, and what would that rule out?
  • What would you do if the primary metric and the guardrail moved in opposite directions?

Can you explain the difference between supervised and unsupervised learning?

Medium

Approach

  1. Say what you would check first and why it is the highest-information step.
  2. Clarify what is being asked and what a complete answer would contain.
  3. State your assumptions explicitly before working the problem.

Follow-up

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

Reminder volume where the guardrail opposes the primary metric

Medium · engagement · guardrails · trade-offs

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

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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)

  1. 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'.
  2. 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.
  3. 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.
  4. Compare week-1 with week-4 lift, state the decay rate, and carry the week-4 figure into the trade.
  5. Write the rule as two thresholds plus a default action for the middle case.

Expected result: A written ship/stop rule containing a numeric exchange rate between one incremental weekly active account and one opt-out, derived from an observed lifetime and an observed decay rather than asserted.

Verify it yourself

  • The cumulative opt-out curve within a fixed set of contactable accounts must be non-decreasing. A dip means the denominator is being recomputed each week and the metric is not a stock.
  • Week-4 incremental lift should be materially below week-1. If it is not, either the horizon is too short to see decay or the arms are contaminated by cross-sends.
  • Repeat rate must be computed on the same accounts across consecutive weeks, not on the weekly active set, whose composition changes every week by construction.

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?

Decide whether a one-day core-action drop is real

Easy · seasonality · day-of-week · late-arriving-data

A daily dashboard counts distinct fct_event.user_id with is_core_action = TRUE, filtered on occurred_at_utc, and is read at 09:00 UTC. This morning it shows yesterday down 22% against the day before. fct_event is partitioned on received_at_utc. You have fct_event, fct_session and dim_user with thirteen months of history. Deliver a one-paragraph verdict, escalate or do not escalate, with the evidence that settles it, before anyone proposes a product hypothesis.

Approach

  1. Identify which two weekdays the comparison actually spans, then pull the same weekday-pair transition for the last 52 weeks and place the observed 22% inside that distribution. A day-over-day comparison in a product with a weekday pattern is a comparison of two different populations, so the reference class is the same transition historically, not the prior day.
  2. Measure partition completeness rather than assuming it. For each of the last 30 days compute the share of that day's occurred_at_utc rows that had landed by 09:00 UTC the following morning, split by surface; mobile clients buffer events offline, so the freshest partition is systematically short and the shortfall is not uniform across surfaces.
  3. Recompute the same series keyed on received_at_utc. If the drop survives on both keys it is not a lateness artefact; if it exists only on occurred_at_utc it is the partition filling in.
  4. Check the two exclusion flags before segmenting anything: a change in is_bot_flagged coverage or a batch of is_internal accounts entering or leaving moves a distinct-user count with no user behaviour behind it.
  5. Only if the movement survives all of the above, begin the segment decomposition. Say explicitly in the verdict which of these four checks the movement passed, so the next reader does not repeat them.

Follow-up

  • What publication lag would you set for this dashboard, and how would you derive the number rather than pick it?
  • If you switch the metric to received_at_utc, what does that break for anyone comparing to historical figures?
  • How would you detect the same problem automatically, so a human does not have to notice it each morning?

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.

Ownership when the result is inconvenient

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.

If given conflicting data, how would you determine which to trust?

Medium · behavioural and stakeholder questions

Approach

  1. Pick a story where you drove the decision, not one where you observed it.
  2. Name the disagreement or constraint, and how you resolved it with evidence.
  3. State the situation in two sentences and spend the rest on your reasoning.

Follow-up

  • What would you do differently if you ran that project again?
  • What did you decide not to do, and why?

Disagree with a product manager's roadmap claim using data

Medium · causal inference · selection bias · stakeholder

A product manager proposes building a feature on the argument that accounts connecting an integration in week one retain three times better at week four. The figure is correctly computed from dim_user and fct_event, and it has already been shown to leadership. You have one scheduled 1:1 before the roadmap locks. Deliver the specific analysis you would run to test whether the relationship is causal, the result that would change your own mind, and how you open the conversation so that the PM is not put in the position of defending the number in public.

Approach

  1. Recognise what is being probed: whether you can separate a number being right from an inference being wrong, and do it without costing the PM face. The generic answer recites that correlation is not causation; the strong one names the specific confound and proposes the cheapest design that could distinguish the explanations.
  2. State the alternative concretely. Accounts that connect an integration in week one are accounts that already have a workflow and a technical owner, so week-one intent plausibly drives both the connection and week-four retention. The selection is on intent, which no amount of post-hoc adjustment observes.
  3. Order the discriminating analyses by cost. First, condition on pre-connection activity by comparing retention within strata of week-one core-action count, which removes the crude version of the confound but not unobserved intent. Second, look for variation in integration availability that was unrelated to intent, such as a staggered release or an outage window. Third, an encouragement design that randomises a prompt to connect and reads the intent-to-treat effect on week-four retention, which is the only version that identifies an effect.
  4. Run the timing check, because it is nearly free and it is the most persuasive single piece of evidence. If the retention advantage among connectors is already visible before any of them connected, the causal story is largely finished.
  5. Pre-commit to what would change your mind and say it before you show anything: if the gap survives stratification and the encouragement arm moves week-four retention at all, the feature has a case and you will say so.
  6. Open the 1:1 by agreeing with the true part, that the correlation is real and worth chasing, then ask what effect size the roadmap plan assumes. That makes the size of the claim the topic instead of its authorship.

Follow-up

  • The encouragement test needs six weeks and the roadmap locks in two. What do you recommend in the interim?
  • Stratifying on week-one activity closes half the gap. What do you conclude, and what do you still not know?
  • How would you word this in the roadmap document so the PM's original number is reframed rather than deleted?

Handle a request for numbers supporting a decision already made

Hard · integrity · framing · stakeholder

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?