Data Scientist Senior Interview Questions

3,397 data scientist senior interview questions shared by candidates

ML: 1. Linear Regression: 1.1. Explain L1 vs L2? 1.2. How does each affect the coefficients? 1.3. Explain assumptions of linear regression. 1.4. How is each assumption tested? 1.5. If each assumption is violated, what are their remedies? 2. PCA 2.1. Explain PCA. 2.2. Walk me through the algorithm step by step. 2.3. How is the formula constructed? 2.4. What is the relationship between PC1 and PC2? 2.5. How is orthogonality preserved in the mapped feature space? 2.6. How do you run the feature importance in PC-mapped feature space? 3. ML Algorithm 3.1. Explain the ensembling method. 3.2. Explain the differences between XGBoost and Random Forest? 3.3. When is each used? Pros and cons? 3.4. Which one is computationally expensive and why? 3.5. What are the feature selection methodologies? 3.6. Imagine we have a multivariate KPI that most of the features are correlated. Now we are noticing a spike in the KPI, how do you determine which feature has the highest effect on it? (Feature importance analysis for Temporal shock)
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Senior Data Scientist

Interviewed at Microsoft

4
Dec 25, 2024

ML: 1. Linear Regression: 1.1. Explain L1 vs L2? 1.2. How does each affect the coefficients? 1.3. Explain assumptions of linear regression. 1.4. How is each assumption tested? 1.5. If each assumption is violated, what are their remedies? 2. PCA 2.1. Explain PCA. 2.2. Walk me through the algorithm step by step. 2.3. How is the formula constructed? 2.4. What is the relationship between PC1 and PC2? 2.5. How is orthogonality preserved in the mapped feature space? 2.6. How do you run the feature importance in PC-mapped feature space? 3. ML Algorithm 3.1. Explain the ensembling method. 3.2. Explain the differences between XGBoost and Random Forest? 3.3. When is each used? Pros and cons? 3.4. Which one is computationally expensive and why? 3.5. What are the feature selection methodologies? 3.6. Imagine we have a multivariate KPI that most of the features are correlated. Now we are noticing a spike in the KPI, how do you determine which feature has the highest effect on it? (Feature importance analysis for Temporal shock)

How does BERT work? What are LLM's, Have you worked on any LLM's? What are Transformers and what are they used for? What is difference between tf-idf and Word2Vec Linear and Logistic Regression Bias Variance Coding test on SQL and Python
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Personalization Platform Senior Data Scientist

Interviewed at Dell Technologies

3.7
Jun 26, 2024

How does BERT work? What are LLM's, Have you worked on any LLM's? What are Transformers and what are they used for? What is difference between tf-idf and Word2Vec Linear and Logistic Regression Bias Variance Coding test on SQL and Python

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