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NYU Langone Health Data Scientist Interview Questions & Guide 2026

Data scientist interview prep for NYU Langone Health: original practice on experiment design, SQL and metric reasoning, with worked solutions.

The 60-second brief

At NYU Langone Health, a Data Scientist transforms complex clinical and research data into actionable insights that improve patient outcomes, accelerate discovery, and inform strategic decisions. You will build models that guide clinicians, develop methods that elevate the standard of research, and design analytics pipelines trusted across our health system and schools of medicine. Your work will touch priorities ranging from clinical decision support and population health to statistical genetics, environmental epidemiology, and operational efficiency.

Ask early whether the loop includes an asynchronous take-home or a timed live case, because the two are graded on different things. A take-home is read as an artifact: the question you decided to answer, what you did about missing or malformed records, and a conclusion stated plainly enough for someone to act on. A reviewer who cannot rerun your notebook discounts the result whatever score is printed in it. Hold to the stated time box and write down what you would have done with more of it, since the follow-up round is usually a live defence of the same work.

Focus areas

  • Correct for claims runout before reporting recent months
  • Separate censoring from events in time-to-event models
  • Build member-month denominators from overlapping coverage spans

Overview

You will collaborate with world-class investigators and clinicians, including teams such as the Center for Human Genetics and Genomics (e.g., polygenic risk prediction and genetic architecture of complex traits) and divisions like Environmental Pediatrics (e.g., longitudinal cohort analyses, biomonitoring, and public health surveillance). This role is critical because health data is high-stakes, high-dimensional, and heterogeneous (EHR, imaging, genomics, registries). The ability to make rigorous, ethical, and interpretable inferences is not just a technical requirement—it is a responsibility to our patients, our communities, and our scientific mission.

Expect to operate at the intersection of statistical rigor, computational scale, and clinical relevance. You will be asked to design studies that stand up to peer review, build models that clinicians can trust, and produce results that translate into policy, practice, or new lines of inquiry. This is work that matters—scientifically and humanistically.

Where to focus your preparation

Treat the sections below as preparation areas and confirm the format with your recruiter.

Preparation focus

No round sequence has been reported for this company, so work the categories below and confirm the format with your recruiter.

What to demonstrate

  • Breadth across SQL, experimentation and product reasoning
  • Ability to state assumptions before choosing a method

How to prepare

  • Drill the practice exercises below and time yourself
  • Prepare three quantified stories about decisions you drove

Where candidates lose points

Treating clinical measurements as missing at random

A lab result, a vital sign, or a screening exists because someone ordered it, and ordering tracks suspicion of disease, visit frequency, and site workflow. Imputing the mean or dropping incomplete rows biases the population estimate and can flip the sign of an association, because the untested are systematically healthier or systematically disengaged. The presence indicator is often more predictive than the value, which is a warning sign rather than a feature win: a model that learns test ordering will not transfer to a site with different protocols.

Pre-post evaluation on a high-cost or high-risk cohort

Cohorts selected on an extreme value of the outcome regress toward the mean on their own. Members identified as the top 1 percent of spend in one year spend far less the next, whether or not anyone intervenes, because the selecting year captured both chronic severity and one-off events. A pre-post design on such a cohort will report savings every time. A concurrent comparison group selected by the same rule in the same period, or a regression discontinuity at the selection threshold, is the minimum credible design.

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.

Crediting a treatment for regression to the mean

Selecting a group because it is extreme (lowest-engagement users, accounts having their worst month, the bottom decile of a score) moves that group's expected next-period value back toward the average even under no treatment, by exactly as much as the selecting measure is imperfectly correlated with its own later value. Compare against units that met the same selection rule and went untreated, or use two pre-periods so the bounce-back is visible before the intervention starts. A pre-post number on a group chosen for being extreme measures the selection rule, not the treatment.

Questions & practice

Show how you would compute and interpret decision curves and net benefit for a risk model.

Medium · machine learning and modelling

Approach

  1. Say how the offline result would be validated online before it is trusted.
  2. Check what information would not exist at prediction time, and exclude it.
  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?
  • What would you monitor after launch to know the model is still valid?

How do you choose between logistic regression, gradient boosting, and a neural model for a binary clinical outcome? Discuss calibration and interpretability.

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. Set a baseline first, so any model has something honest to beat.

Follow-up

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

Walk through your approach to handling extreme class imbalance for detecting rare adverse events.

Medium · machine learning and modelling

Approach

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

Follow-up

  • Where could label leakage enter this setup?
  • What would you monitor after launch to know the model is still valid?

Simulate how ignoring clustering inflates the false positive rate

Medium · simulation · design effect · type i error

Simulate a provider-level comparison with no true effect. 40 providers, 60 members each, a continuous outcome with total variance 1 and intraclass correlation 0.02. Randomise providers 20 to 20, not members. Over 5,000 replications, report the share of replications where a two-sample t-test run on all 2,400 individual observations, ignoring provider, returns p below 0.05. Report the same share when the unit of analysis is the 40 provider means. Then state how the first number follows from the design effect 1 + (m - 1) x ICC.

Approach

  1. Decompose the variance explicitly rather than tuning it: provider variance = ICC = 0.02, residual variance = 1 - ICC = 0.98. Draw u_j once per provider and e_ij per member, so the outcome is u_j + e_ij and the correlation between two members of one provider is 0.02 by construction.
  2. Randomise at the provider level. That is the entire mechanism: the treatment indicator is constant within a provider, so in any single replicate the provider intercepts are confounded with the arm, and the naive test reads that confounding as signal.
  3. Vectorise over replications with a (reps, providers, members) array. 5,000 x 2,400 normals is trivial in numpy, and a Python loop is what tempts people to cut replications to 500 and report a number with Monte Carlo noise of plus or minus 0.017.
  4. Predict the answer before running it: design effect = 1 + (60 - 1) x 0.02 = 2.18, naive standard errors are too small by sqrt(2.18) = 1.476, so the rejection rate at nominal 0.05 is about 2 x (1 - Phi(1.96 / 1.476)) = 0.18. Agreement between prediction and simulation is what makes the result a demonstration rather than an anecdote.
  5. Run the provider-mean analysis as the control. Recovering 0.05 there proves the generator is correct and isolates the failure to the analysis unit.

Worked solution (30 min)

  1. Draw u with shape (reps, 40) from N(0, sqrt(0.02)) and e with shape (reps, 40, 60) from N(0, sqrt(0.98)); y = u[:, :, None] + e.
  2. Assign providers 0-19 to one arm and 20-39 to the other; because there is no true effect, a fixed split is valid and removes one source of Monte Carlo noise.
  3. Naive test: flatten each arm to 1,200 observations and compute a two-sample t statistic per replication with vectorised means and pooled variance.
  4. Cluster test: average within provider to 40 values, then run the same two-sample t on 20 versus 20.
  5. Report both rejection shares and compare the naive one against 2 x (1 - Phi(1.96 / sqrt(2.18))).

Expected result: The naive individual-level test rejects in roughly 18 percent of replications, against a nominal 5 percent. Monte Carlo standard error at 5,000 replications is about 0.005, so anything in 0.17 to 0.19 is consistent. The provider-mean analysis rejects in about 5 percent, within roughly 0.003.

Verify it yourself

  • Set ICC to 0 and both analyses return about 0.05. If the naive one does not, the data generator is wrong, not the test.
  • Raise members per provider from 60 to 120 with ICC fixed and the naive rate rises, because the design effect grows linearly in cluster size.
  • The provider-mean analysis stays near 0.05 at every ICC you try, which is the definition of a valid test.
  • The simulated naive rate lands within about 0.01 of 2 x (1 - Phi(1.96 / sqrt(design effect))).

Follow-up

  • How many providers would you need for 80 percent power on a 0.2 SD difference with 60 members each and this ICC?
  • Cluster sizes are unequal in reality. The design effect approximation becomes 1 + ((1 + CV^2) x mbar - 1) x ICC. Which direction does that move your sample size and why?
  • The intervention cannot be withheld from any provider. Sketch a design that still yields a defensible estimate.

Deduplicate claim versions before totalling allowed amounts

Easy · dedup · window functions · claim versions

medical_claim_line holds one row per service line per claim version: claim_line_id, claim_id, claim_version, frequency_code (1 original, 7 replacement, 8 void), member_id, service_start_date, procedure_code, allowed_amount, claim_status and adjudicated_at. Adjusted claims appear more than once, so summing every row double counts them. Return total allowed_amount by procedure_code for service_start_date in Q1 2025, counting only lines with claim_status 'paid' on the surviving version of each claim, which is the highest claim_version per claim_id, and dropping the claim entirely when that surviving version carries frequency_code 8. Resolve survivorship with a window function, not a self-join.

Approach

  1. Resolve survivorship at claim_id, not claim_line_id. Carry MAX(claim_version) OVER (PARTITION BY claim_id) alongside every line and keep lines where claim_version equals it, because a replacement version can contain a different number of lines than the original.
  2. Read the frequency_code of the surviving version only. A frequency_code 8 removes the claim outright; it does not revert payment to the prior version, so a void must delete the claim rather than promote version n-1.
  3. Apply claim_status and the date filter after survivorship is resolved. Filtering paid lines first can strip the surviving version and silently elect a superseded one.
  4. Group by procedure_code and sum allowed_amount, then state the paid-through date on the output because Q1 amounts keep moving until adjudication runout completes.
  5. Sanity check the shrinkage: report how many claim_ids and how many dollars the dedup removed, so the reviewer can see the step did something.

Follow-up

  • Two rows share a claim_id and claim_version but differ on adjudicated_at. What do you do, and what does that imply about the extract?
  • How does the query change if the request is allowed_amount by paid_date rather than service_start_date, and which basis does a finance reconciliation want?
  • A void arrives for a claim already published in a closed month. How do you restate without rewriting history in the warehouse?

Find inpatient encounters with no resulted lab during the stay

Medium · anti-join · null semantics · event matching

encounter holds encounter_id, patient_id, encounter_type, admit_ts, discharge_ts and facility_id. lab_result holds result_id, order_id, patient_id, encounter_id (NULL for outpatient standing orders), loinc_code, specimen_collected_ts, resulted_ts and result_status. Return every inpatient encounter discharged in 2025 with no final or corrected lab_result linked to it. A colleague wrote WHERE encounter_id NOT IN (SELECT encounter_id FROM lab_result) and got zero rows back. Say why, write the correct query, then say what changes when labs must instead be matched on patient_id with the specimen collected between admit_ts and discharge_ts.

Approach

  1. Name the mechanism rather than the symptom. x NOT IN (subquery) expands to x <> y1 AND x <> y2 AND ..., and a single NULL y makes that chain UNKNOWN, never TRUE. Since lab_result.encounter_id is nullable by design for standing orders, this query can only ever return zero rows.
  2. Rewrite as NOT EXISTS, or LEFT JOIN with an IS NULL filter. Both treat a NULL key as no match rather than as unknown. Adding IS NOT NULL inside the NOT IN subquery also works, but NOT EXISTS is the habit that survives someone making another column nullable later.
  3. Put the result_status predicate inside the correlated subquery or the ON clause, not in an outer WHERE. Outside, it turns the anti-join back into an inner join and an encounter whose only labs were cancelled disappears instead of qualifying.
  4. For the timestamp variant, match on patient_id with specimen_collected_ts inside the stay rather than resulted_ts. A specimen drawn an hour before discharge can result the next day, and anchoring on resulted_ts would wrongly call that stay lab-free.
  5. Restrict to encounter_type 'inpatient' and discharge_ts in 2025, and report open encounters with a NULL discharge_ts as a separate count instead of letting the filter swallow them.

Worked solution (20 min)

  1. Demonstrate the cause: SELECT COUNT(*) FROM lab_result WHERE encounter_id IS NULL returns a non-zero number.
  2. Write the NOT EXISTS version with result_status IN ('final','corrected') inside the correlated subquery.
  3. Write the LEFT JOIN version with the same predicate in the ON clause and WHERE l.result_id IS NULL, then compare counts.
  4. Build the timestamp variant joining on patient_id with specimen_collected_ts >= admit_ts AND < discharge_ts.
  5. Report both counts side by side and explain which encounters differ between the two definitions.

Expected result: One row per qualifying inpatient encounter with encounter_id, patient_id, facility_id, admit_ts and discharge_ts. The count is strictly below total 2025 inpatient discharges and strictly above zero, while the NOT IN version returns exactly zero rows.

Verify it yourself

  • NOT EXISTS and LEFT JOIN with IS NULL return identical row counts.
  • Adding AND encounter_id IS NOT NULL inside the NOT IN subquery reproduces the NOT EXISTS count exactly.
  • No returned encounter_id appears anywhere in lab_result with result_status in ('final','corrected').
  • The patient-and-timestamp variant returns fewer encounters than the encounter_id variant, since it also catches labs whose encounter link is missing.

Follow-up

  • Write the LEFT JOIN form and say exactly where the result_status predicate must sit for the two forms to agree.
  • How would you separate encounters whose only labs were cancelled from encounters with no lab rows at all?
  • Some encounters carry member_id NULL because the person index did not match. What does that do to a payer-side version of this measure?

Design an observational study to estimate treatment effect from EHR data; specify confounders and your adjustment strategy.

Medium · a/b testing and experimentation

Approach

  1. Name the randomisation unit first; it decides the variance and what the test can detect.
  2. Decide the analysis before seeing data, including how long it runs and when you look.
  3. State the primary metric and the minimum effect worth shipping, then size the test.

Follow-up

  • What would you do if you could not randomise at all?
  • What would you conclude if the result is positive but the test is underpowered?

Size a clinic-randomised trial when the intracluster correlation binds

Medium · cluster randomisation · design effect · stepped wedge

A care-coordination change is delivered at the clinic level and cannot be withheld from some members of a participating clinic. Forty-eight clinics are available for 1:1 randomisation. The primary outcome is the 90-day primary care contact rate among newly enrolled members, baseline 0.62, with a target of plus 5 percentage points. Each clinic contributes about 60 eligible members a year, and the intracluster correlation on this outcome is 0.02. Two-sided alpha 0.05, 80 percent power. Give clinics required per arm, say whether 48 suffices, and what you would do.

Approach

  1. Compute the individually randomised sample size first, then inflate it by the design effect 1 + (m - 1) x ICC, where m is the average cluster size. The design effect is the price of correlation within clinics and is the single largest term in this calculation.
  2. Convert the inflated individual N into clusters by dividing by m, and compare with the 24 clinics available per arm.
  3. Check the ceiling before proposing a longer accrual window. As m grows, effective members per cluster approaches 1 / ICC, here 50, so 24 clinics can never contribute more than 1,200 effective members per arm no matter how many members each one enrols. If the required effective N exceeds that, no amount of accrual rescues the parallel design.
  4. Propose the designs that actually change the arithmetic: a stepped wedge in which every clinic crosses over so each contributes a within-cluster comparison, or a smaller randomisation unit (provider pod) if the intervention can be delivered at that level without contamination.
  5. Add the two refinements a reviewer will ask for: use a t-distribution with roughly 2k - 2 degrees of freedom rather than z when k is small (here about 46 df, which raises N by about 4 percent), and use covariate-constrained randomisation on baseline contact rate so 48 clinics do not land badly imbalanced by chance.

Worked solution (30 min)

  1. Individual n per arm = 7.849 x (0.62 x 0.38 + 0.67 x 0.33) / 0.05^2 = 7.849 x 0.4567 / 0.0025 = 1,434.
  2. Design effect = 1 + (60 - 1) x 0.02 = 2.18.
  3. Inflated n per arm = 1,434 x 2.18 = 3,126 members, so clusters per arm = 3,126 / 60 = 52.1, round up to 53.
  4. Compare with 24 clinics available per arm: the study is short by more than a factor of two.
  5. Compute the ceiling: 1 / 0.02 = 50 effective members per clinic, so 24 clinics give at most 1,200 effective members per arm against the 1,434 required.

Expected result: 53 clinics per arm (106 total) against 48 available. The effective-sample ceiling of 1,200 per arm is below the 1,434 needed, so the parallel cluster design is infeasible at any panel size; the answer is a stepped wedge, a smaller randomisation unit, or a pre-registered larger MDE.

Verify it yourself

  • Verify the design effect directly: 1 + 59 x 0.02 = 2.18.
  • Verify the diminishing return: doubling m from 60 to 120 raises effective members per cluster only from 27.5 to 35.5, not from 60 to 120.
  • Recompute with t-based quantiles at 46 df and confirm the requirement moves by a few percent, not by a factor.

Follow-up

  • Sketch the stepped-wedge analysis model. What does a secular trend do to the estimate if you leave period effects out?
  • The ICC was estimated from a prior year at 0.02 with a wide interval. How do you size under ICC uncertainty?
  • Six clinics withdraw after randomisation. What does that do to power compared with losing the same number of members?

Adherence share collapsed the month a feed was added

Easy · pdc · interval sql · identity resolution

The share of members with proportion of days covered at or above 0.80 in one therapeutic class fell from 0.71 to 0.58 in a single month. pharmacy_claim carries fill_id, member_id, ndc_code, therapeutic_class_code, fill_date, days_supply, quantity_dispensed, refill_number, reversal_flag, reversed_fill_id and source_system_code. There is no person-level key above member_id and no enrollment table on hand, so every diagnostic has to run on pharmacy_claim alone. That month the pipeline began ingesting a second pharmacy source. Determine whether adherence actually changed, and hand back a PDC query you would defend line by line.

Approach

  1. Compute controls that depend on neither member identity nor the PDC code: total fills in the class per month, and total days_supply dispensed in the class per month. Both are sums over rows, so neither moves when one person's fills split across two member_ids, which is exactly what a per-member control cannot promise. If both are flat while PDC falls, no dispensing behaviour changed and the computation or the keys did.
  2. Check days_supply for nulls and zeros by source_system_code. If the new source omits days_supply and the code coalesces null to zero, covered days vanish and PDC falls even though the fills are there.
  3. Check for member identity splitting using the columns you actually have. There is no person key above member_id, so the split has to be found by its footprint: distinct member_id in the class jumping at the break while total fills stay flat, and a rise in the share of member_ids whose earliest fill for a given ndc_code carries refill_number above zero, which is a continuation history that lost its beginning. When one person is split, each id may fall below the two-fill denominator requirement and drop out, and the ids that do survive carry artificial gaps.
  4. Check reversals. A reversed fill is two rows, the fill and a row with reversal_flag TRUE pointing at reversed_fill_id, and both must be excluded from exposure. If the new source expresses reversals differently and reversed_fill_id does not link, phantom coverage appears, which pushes PDC up rather than down, so use this to rule the cause in or out.
  5. Verify the denominator and window are unchanged: members with at least two fills in the class and at least 91 days of follow-up, over a stated fixed 12-month window, never a mixture of window lengths.
  6. Write the PDC query so overlapping refills shift the next interval's start to the later of fill_date and the prior interval's end, so a day is covered at most once, and cap at one day per calendar day.

Follow-up

  • Why is PDC preferred to medication possession ratio when early refills are common?
  • You want to compare adherent and non-adherent members on hospitalisation. What is wrong with classifying on a 12-month PDC and then following from day zero?
  • A member switches to a different drug in the same class mid-year. How does your interval logic handle that, and is the class the right grain?

Suggested practice checklist

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

Day 1 — Diagnostic, scored before you study anything

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

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

Day 2 — Largest gap: find the boundary rather than the subject

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

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

Day 3 — Largest gap: drill the blocking sub-skill

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

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

Day 4 — Second gap, plus maintenance on your strongest area

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

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

Day 5 — The gap that is not a skill

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

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

Day 6 — Retest under day-one conditions

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

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

Day 7 — Full loop under interview conditions

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

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

Stories where someone disagreed with you

Have two ready. In one, the data was on your side and you had to move someone who outranked you. In the other, the pushback was correct and you changed position. The second is the harder story and it lands better, because it shows you separate being right from being attached to an answer. Name the person's actual objection.

Describe a time when model performance degraded in production. How did you diagnose and fix it?

Medium · behavioural and stakeholder questions

Approach

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

Follow-up

  • How did you know the outcome was caused by your change?
  • What did you decide not to do, and why?

Scope a one-line request for a readmission rate

Easy · scoping · measure specification · stakeholder communication

A clinical operations lead messages you: 'What is our readmission rate? The committee meets Friday.' You have encounter (encounter_id, admit_ts, discharge_ts, encounter_type, admission_type, discharge_disposition, drg_code, index_encounter_id) and member_enrollment coverage spans. Do not open a query editor yet. Deliverable: the three to five questions you send back, ranked by how much the answer moves the number; the default specification you will build if nobody replies by Wednesday; and the one line you will place under the figure so the committee does not read it against a published benchmark.

Approach

  1. Read the probe: this tests whether you convert ambiguity into a specification without either stalling or guessing silently. Both failure modes are common, and the silent guess is worse because nobody can see it.
  2. Rank your questions by leverage on the number rather than by curiosity. Whether the numerator is all-cause or unplanned, and whether the clock starts at discharge_ts, move the result far more than a tie-break rule on same-day returns.
  3. Ask about the comparison first. A number going to a committee will be compared to something, and whether that something is last quarter, another panel, or a national figure decides whether you owe them a raw rate, a risk-adjusted rate, or an observed-over-expected ratio.
  4. Commit to a default in writing so silence does not block you: unplanned acute inpatient readmission within 30 days of discharge_ts, index stays excluding planned admissions, acute-to-acute transfers, discharges against medical advice, and dispositions of expired or hospice, denominator of eligible index discharges, paid-through date stated.
  5. Write the caveat as a restriction on use rather than a hedge: name the one comparison the figure supports and the one it does not.

Follow-up

  • They reply that they want it 'the way the benchmark does it'. What do you ask next?
  • The committee wants it split by attending provider. What changes in the specification, and what do you refuse to show?
  • How does your answer change if the meeting is tomorrow rather than Friday?

Make an honest case for your own analytical impact

Hard · impact attribution · counterfactual · self-assessment

You are asked to account for a year of your work. Constraint: you may only use measures that existed before you knew the outcome, and you must include one project that moved nothing. The portfolio contains a measure specification that changed how a contract settles, a predictive model that shipped, a self-serve dashboard, and an evaluation that killed a proposed programme. Deliverable: how you attribute value to each, which of them you claim credit for and which you do not, and the one number you would accept being judged on next year.

Approach

  1. The probe is whether you can reason counterfactually about your own work, which is the same discipline this domain demands of you for programmes, applied where it is uncomfortable.
  2. State the counterfactual for each item: what would have happened without you. A measure specification that changed how a contract settles has a dollar counterfactual you can compute. A dashboard's counterfactual is analyst hours, which is real and small, and attaching a revenue number to it is where these accounts usually turn into fiction.
  3. Treat the killed programme as your strongest item and say why. Avoided spend is real value, it is attributable because the decision turned on your evaluation, and it is the one item nobody else will count on your behalf.
  4. Report the shipped model the way you would report anyone's model: calibration in the subgroups that matter, adoption by the people it was built for, and whether any decision changed. A model that is live but ignored has zero impact, and saying so is the credibility test in this answer.
  5. Name the failed project with its mechanism and its cost, then say what earlier signal you would watch to kill it sooner. Time to kill is a legitimate impact measure.
  6. Choose next year's number so that it can go down. A metric that only ratchets upward is not a commitment.

Follow-up

  • Two other people also claim the contract measure. How do you split it?
  • Your model is live and used, but the decisions it informs would have been the same without it. Is that impact?
  • What is the strongest argument that your year had less impact than you just described?