✅ Top 50 Data Analytics Interview Questions – Part 5 📊🧠

3️⃣1️⃣ Explain the difference between Mean, Median, and Mode.
⦁ Mean: Average value.
⦁ Median: Middle value when sorted.
⦁ Mode: Most frequent value.

3️⃣2️⃣ What is Variance and Standard Deviation?
⦁ Variance: Average of squared differences from the mean.
⦁ Standard Deviation: Square root of variance. Shows data spread.

3️⃣3️⃣ What is Data Sampling?
Selecting a subset of data for analysis.
Types: Random, Stratified, Systematic.

3️⃣4️⃣ What are Dummy Variables?
Binary variables (0 or 1) created to represent categories in regression models.

3️⃣5️⃣ Difference between SQL and NoSQL?
⦁ SQL: Relational, structured data, uses tables.
⦁ NoSQL: Non-relational, flexible schemas (e.g., MongoDB).

3️⃣6️⃣ What is Data Pipeline?
A series of steps to collect, clean, transform, and store data for analysis.

3️⃣7️⃣ Explain the term ETL.
⦁ Extract: Get data from source
⦁ Transform: Clean/modify data
⦁ Load: Store in target database

3️⃣8️⃣ What is Data Governance?
Policies and procedures ensuring data quality, privacy, and security.

3️⃣9️⃣ What is Data Lake vs Data Warehouse?
⦁ Data Lake: Stores raw data (structured + unstructured).
⦁ Data Warehouse: Stores structured, processed data for analysis.

4️⃣0️⃣ What are Anomaly Detection techniques?
⦁ Statistical methods
⦁ Machine learning models (Isolation Forest, One-Class SVM)
Used to detect unusual patterns or fraud.

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