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Updated weekly · Last refresh Oct 17

Costar Group Data Analyst Interview Questions

The questions to prepare for a Costar Group Data Analyst interview. Questions from real interview reports rank first. Updated daily.

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1
SQL & Data ManipulationStart here. 7 questions + 2 drills · ~82 min
Calculate Monthly Sales Growth by Product CategoryMedium
Practice
Recently asked

Calculate month-over-month sales growth for each product category using JOINs and window functions.

JoinsAggregationsCostar Group
Cleaning Nulls and Duplicate RecordsEasy
Recently asked

Explain how to clean nulls, remove duplicates, and standardize inconsistent values during SQL transformations.

Data WranglingCase WhenAggregationsCostar Group
QA Data Issues on Homes.comMedium
Recently asked

Tests your approach to validating data quality and diagnosing issues in a production analytics context.

data integrityCostar Group
SQL Query OptimizationMedium
Recently asked

Tests your approach to diagnosing and improving SQL performance.

Performance Tuningquery optimizationtechnical experienceCostar Group
Fixing Slow QueriesHard
Recently asked

Tests your troubleshooting skills and practical performance tuning strategies.

query optimizationTroubleshootingCostar Group
SQL Joins and FilteringMedium
Recently asked

Tests your ability to write correct SQL joins and apply precise filtering logic.

Joinssql queryCostar Group
Optimize a Slow SQL QueryHard
Practice
Practice drill

Rewrite a slow PostgreSQL loan payment query to reduce scanned rows while preserving the required aggregated results.

database optimizationJoinsData WranglingAmeripriseEEltro Cyberchrome PrivateEnergyHub
Top Customers by Sales RevenueEasy
Practice
Practice drill

Use GROUP BY and SUM to rank the top 10 customers by total revenue from a single sales table.

RankingGroup ByAggregationsHousecall ProEquifaxXYZ
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2
Behavioral & Leadership6 questions · ~54 min
Prioritizing Competing Data RequestsMedium
Recently asked

Tests prioritization under pressure in a data engineering context, including stakeholder management, trade-off decisions, and ownership of outcomes.

Decision MakingStakeholder ManagementPrioritizationCostar Group
Explaining Technical Issues ClearlyMedium
Recently asked

Tests whether you can translate technical complexity into business-relevant language for non-technical stakeholders and drive action.

Stakeholder ManagementCommunicationtechnical explanationCostar Group
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The finish line: interview-readyComplete all 13 questions plus 2 hands-on drills to finish this plan.