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Quest Diagnostics Data Scientist Interview Questions

The questions to prepare for a Quest Diagnostics Data Scientist interview. Questions from real interview reports rank first. Updated weekly.

26questions
~4htotal time
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1
Machine LearningStart here. 4 questions · ~33 min
Preprocessing Data for Model TrainingEasy

Explain a practical preprocessing pipeline for supervised learning, from data cleaning and encoding to validation-ready features.

Hyperparameter TuningCross-ValidationFeature EngineeringQuest Diagnostics
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2
Statistics & Probability3 questions · ~25 min
Mean and Standard Deviation BasicsEasy

Compute the mean and standard deviation of a dataset, and distinguish the sample standard deviation from the population version.

DistributionsVarianceExpected ValueQuest Diagnostics
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3
A/B Testing & Experimentation3 questions · ~25 min
Pitfalls in Streaming Experiment AnalysisHard

Identify major online experiment pitfalls and explain how they can bias results in a streaming product A/B test.

Network InterferenceNovelty EffectSample Ratio MismatchQuest Diagnostics
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4
Behavioral & Leadership10 questions · ~83 min
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5
More topics6 questions · ~50 min
Explain Precision Recall TradeoffEasy

Explain precision versus recall in plain language and how the tradeoff affects product decisions.

PrecisionThreshold TuningRecallQuest Diagnostics
Diagnose KPI Drop After ReleaseMedium

Diagnose a post-release KPI drop by separating instrumentation issues from real behavior changes and tracing the problem through the metric hierarchy.

KPILeading IndicatorsDiagnosisQuest Diagnostics
Healthcare Product Metrics and North StarMedium

Assesses your product analytics thinking and ability to connect KPIs to measurable healthcare outcomes.

North Star MetricKPIsProduct VisionQuest Diagnostics
Optimizing a Slow SQL QueryMedium

Tests SQL performance troubleshooting skills and systematic optimization approach.

Window FunctionsJoinsAggregationsQuest Diagnostics
Ensuring ReproducibilityEasy

Tests practices for repeatable, auditable analysis pipelines and documentation.

OrchestrationData ModelingQualityQuest Diagnostics
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Hands-on SQL practiceWrite and run real queries in the editor. 3 drills · ~30 min
Longest Consecutive Login Streak per UserHard
Practice
Practice drill

Calculate the longest consecutive login streak for each user using window functions and date manipulations.

Window FunctionsJoinsAggregationsChimeECSSalesforce
SQL for Weekly Regional PerformanceMedium
Practice
Practice drill

Calculate weekly volume, handling time, and week-over-week change by Kuiper Commercial Services region.

Window FunctionsJoinsAggregationsAmazon Kuiper Commercial Services
Weekly Service KPI by TeamMedium
Practice
Practice drill

Analyze weekly service delivery performance by team using joins, a CTE, date aggregation, and KPI calculations.

KPIJoinssqlDeloitteReputation
The finish line: interview-readyComplete all 26 questions plus 3 hands-on drills to finish this plan.