Nextroll Data Scientist Interview Questions
The questions to prepare for a Nextroll Data Scientist interview. Questions from real interview reports rank first. Updated weekly.
Handle rare positive labels in ad fraud detection with the right sampling, loss design, validation, and thresholding strategy.
NextrollExplain the bias-variance tradeoff mathematically and how L1 and L2 regularization change model complexity and weights.
NextrollTests your ability to model ad request arrivals and reason about statistical assumptions and limitations.
NextrollTests data engineering skills for scalable joins and aggregations under memory constraints.
NextrollCompute daily active users and a 7-day rolling average using a CTE, distinct counts, and window functions.
Meta
Spotify
Meta ITFind the top 3 customers in each region by transaction volume using joins, aggregation, and window ranking.
JPMorganChase
Silicon Valley Bank
NaviCalculate month-1 retention for January vs February signup cohorts using joins, date filtering, and aggregation.
Trideum
Zulily
eBayDiagnose a post-release KPI drop by separating instrumentation issues from real behavior changes and tracing the problem through the metric hierarchy.
NextrollDesign a control-treatment experiment to estimate campaign lift and determine whether the campaign caused a meaningful improvement.
NextrollTests your ability to translate business constraints into a bidding strategy for performance marketing.
NextrollTests system design and anomaly detection for detecting bot-like traffic in ad delivery.
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