Core IT World (VZ Services LLP) Data Scientist Interview Questions
The questions to prepare for a Core IT World (VZ Services LLP) Data Scientist interview. Questions from real interview reports rank first. Updated daily.
Use aggregation and ranking to find each user's most frequent transaction category, resolving ties alphabetically.
Compute each user's seven-day activity average and compare it with the corresponding rolling average from the prior week.
Explain performance and tradeoffs between subqueries, CTEs, and temporary tables in a PostgreSQL data pipeline.
Rank campaigns by advertiser performance and calculate campaign-level running conversions over time with PostgreSQL window functions.
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Amazon AdvertisingTests accountability, prioritization, stakeholder communication, and learning after missing a commitment.
Diagnose a sudden monthly active user decline by validating the metric, isolating affected segments, and identifying likely product or data causes.
Design a guardrail-aware A/B test for conversion at key touchpoints, with explicit MDE, power, and analysis rules.
Design a launch metric system that measures user value, business impact, and product health.
Calculate the sample size needed for statistical significance using baseline rate, MDE, alpha, power, and experiment constraints.
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