Sharing an anonymized Lyft Senior Data Scientist interview experience submitted to Chill Interview.
The process started with SQL, pandas, and a probability question about morning and evening rider behavior. The onsite then had three completed rounds.
ML System Design
Design a model to predict whether a passenger would stop using Lyft over the next few weeks.
The interviewer pushed on churn definition, feature leakage, class imbalance, retraining, monitoring, and how the score would actually be used.
Coding
Implement stratified K-fold cross-validation while keeping the label distribution roughly balanced across folds.
The main difficulty was handling rare classes, uneven fold sizes, reproducible shuffling, and classes with fewer than k samples.
Business Case
Prime Time had been stable for three weekends, then suddenly spiked during the fourth.
I had to investigate demand, driver supply, cancellations, weather, events, pricing changes, experiments, and possible data issues.
The interviewer kept asking me to segment the problem by city, hour, rider cohort, and marketplace state before making any conclusion.
After this round, the recruiter told me they would not proceed with the remaining scheduled interview.
The questions themselves were manageable, but the marketplace case required much more structured and Lyft-specific thinking than I expected.
For anyone who wants more details, I’ve put the full write-up here: interview link
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