The Impossible Shared Case Study
Give every candidate the same unsolvable problem and grade how far they drill and how they react.
- Difficulty
- Moderate
- Time to result
- ~days to results
- Steps
- 4
- Confidence
- 90%
An interview method where every candidate, from entry-level to VP, gets the identical, extraordinarily hard case study. Nobody can finish it; that's the point. You score how many 'corners' they see around, whether they stay non-defensive when you invalidate their solution, and whether they'll interrupt to ask better questions. A seniority rubric maps performance to levels.
Origin
MacInnis encountered this interview tactic when he first moved into Rippling's product org and hadn't used it before. Recruiting still pushes back that it eliminates people too aggressively, but he found real wisdom in it.
Core principles
- 01One identical, deliberately unsolvable prompt is given across all seniority levels.
- 02The goal isn't completion — it's observing depth of reasoning and behavior under pressure.
- 03Reaction to new, solution-invalidating information matters as much as the reasoning itself.
- 04A rubric translates 'how far they got' into level (entry PM vs senior vs exec).
How to run it
- 1
Hand over the concrete wall
Give the candidate a single very difficult, multi-dimensional case (data propagation, technical depth). Expect them to get only 'a millimeter or an inch' in.
Pro tip Use the same case for an L5 and a VP — the contrast is informative, not unfair.
- 2
Watch which corners they see around
Note how many of the hardest hidden corners they anticipate. Seeing around four of the ten hardest is impressive.
- 3
Perturb their solution
Feed them new information that calls their solution into question and observe their response. Look for non-defensiveness and willingness to interrupt you to ask more questions.
Pro tip Basic human-interaction signals (curiosity, composure, non-defensiveness) surface exactly here.
Watch out Candidates almost always leave feeling they failed even when they did well — set expectations or you'll misread their affect.
- 4
Score against the rubric
Map observed depth and behavior to the seniority rubric to place the candidate.
Watch out Recruiting may object that it screens out too aggressively; weigh that against the signal quality.
In the wild
A candidate saw around three or four of the hardest corners impressively, missed ten others, but stayed non-defensive when given solution-invalidating info and interrupted to ask more questions.
→ Read as a strong performance despite the candidate feeling they'd failed.
Common mistakes
Expecting completion
Treating the case as solvable misreads the whole exercise; it's a drill bit against concrete, meant to reveal process, not a finish line.
Ignoring behavior under perturbation
Grading only the technical answer misses the defensiveness/curiosity signal that best predicts real collaboration.
Is it for you?
Best for
Product and technical hiring teams that need a consistent, level-agnostic signal on reasoning and coachability.
Not ideal for
Roles or cultures where candidate experience must be gentle, or high-volume screening where the false-negative rate is unacceptable.
From the transcript
“every product person at every seniority level is given the same case study. And the case study is extraordinarily difficult.”
“give them the concrete wall and see if they can get a millimeter or an inch into the concrete. You know, they're never going to…”
“they were not defensive when we gave them new information that called into question the validity of their solution. And they were willing to interrupt…”
From the episode
10 contrarian leadership truths every leader needs to hear
Matt MacInnis (Rippling)