✅ Data Science Interview Prep Guide

1️⃣ Core Data Science Concepts
• What is Data Science vs Data Analytics vs ML
• Descriptive, diagnostic, predictive, prescriptive analytics
• Structured vs unstructured data
• Data-driven decision making
• Business problem framing

2️⃣ Statistics Probability (Non-Negotiable)
• Mean, median, variance, standard deviation
• Probability distributions (normal, binomial, Poisson)
• Hypothesis testing p-values
• Confidence intervals
• Correlation vs causation
• Sampling bias

3️⃣ Data Cleaning EDA
• Handling missing values outliers
• Data normalization scaling
• Feature engineering
• Exploratory data analysis (EDA)
• Data leakage detection
• Data quality validation

4️⃣ Python SQL for Data Science
• Python (NumPy, Pandas)
• Data manipulation transformations
• Vectorization performance optimization
• SQL joins, CTEs, window functions
• Writing business-ready queries

5️⃣ Machine Learning Essentials
• Supervised vs unsupervised learning
• Regression vs classification
• Model selection baseline models
• Overfitting, underfitting
• Bias–variance tradeoff
• Hyperparameter tuning

6️⃣ Model Evaluation Metrics
• Accuracy, precision, recall, F1
• ROC AUC
• Confusion matrix
• RMSE, MAE, log loss
• Metrics for imbalanced data
• Linking ML metrics to business KPIs

7️⃣ Real-World Deployment Knowledge
• Feature stores
• Model deployment (batch vs real-time)
• Model monitoring drift
• Experiment tracking
• Data model versioning
• Model explainability (business-friendly)

8️⃣ Must-Have Projects
• Customer churn prediction
• Fraud detection
• Sales or demand forecasting
• Recommendation system
• End-to-end ML pipeline
• Business-focused case study

9️⃣ Common Interview Questions
• Walk me through an end-to-end DS project
• How do you choose evaluation metrics?
• How do you handle imbalanced data?
• How do you explain a model to leadership?
• How do you improve a failing model?

🔟 Pro Tips
✔️ Always connect answers to business impact
✔️ Explain why, not just how
✔️ Be clear about trade-offs
✔️ Discuss failures learnings
✔️ Show structured thinking

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