Capital One·Data Scientist·Technical Phone Screen
Jul 2026
Capital One data scientist interview that went deep into subscription unit economics and insurance math. Six parts back to back, some straightforward, some genuinely tricky once churn and fixed costs entered the picture. Left feeling okay about the first half and less sure about the back half.
- A subscription service charges $40/month with the first 3 months free, a $25/month variable service cost, $35 one-time installation, and $120 variable marketing/overhead per customer. The contract is 15 months with no churn. What is the net value per new customer?
- Using the same subscription parameters but extending the contract to 18 months, recompute the net value per customer and explain exactly why the result changes.
- Now extend the contract to 21 months with 10% of customers breaking the contract uniformly across paid months and paying a $100 penalty. Marketing drops to $20/customer variable, overhead becomes $1,000,000/year fixed, installation stays $35. For N customers acquired, derive a formula for the minimum N to break even company-wide.
- Qualitatively describe the demand vs. price curve and the total profit vs. price curve for this subscription service. Where is revenue maximized versus where profit is maximized, and why can those two points differ?
- An insurer sells a 12-month policy at $30/month premium. Servicing costs $3/month. A covered claim pays $8,000 in benefits plus $300 in regulatory costs. There's also a $4/quarter regulatory expense regardless of claims. Let p be the probability of at least one claim in the year. Write and solve the equation where expected profit equals zero.
- Given 400 policies observed over a year with 18 claims, compute the MLE for the claim probability, build a 95% Wald confidence interval, explain when the Wald interval breaks down, and suggest a better alternative.
“Pretty mechanical once you lay it out.” The rest of the author's notes on Data Scientist interview at Capital One, Technical Phone Screen round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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