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Model Selection and Hyperparameter Tuning Questions

Covers the end to end process of choosing, training, evaluating, and optimizing machine learning models. Topics include selecting appropriate algorithm families for the task such as classification versus regression and linear versus non linear models, establishing training pipelines, and preparing data splits for training validation and testing. Explain model evaluation strategies including cross validation, stratification, and nested cross validation for unbiased hyperparameter selection, and use appropriate performance metrics. Describe hyperparameter types and their effects such as learning rate, batch size, regularization strength, tree depth, and kernel parameters. Compare and apply tuning methods including grid search, random search, Bayesian optimization, successive halving and bandit based approaches, and evolutionary or gradient based techniques. Discuss practical trade offs such as computational cost, search space design, overfitting versus underfitting, reproducibility, early stopping, and when to prefer simple heuristics or automated search. Include integration with model pipelines, logging and experiment tracking, and how to document and justify model selection and tuned hyperparameters.

MediumSystem Design
89 practiced
Draft an MLflow-based experiment tracking plan for hyperparameter tuning experiments used by the BI team. Specify which parameters, metrics, artifacts, and tags to log, how to capture dataset and code versions, and how stakeholders will access and interpret the results in dashboards or summary reports.
EasyTechnical
83 practiced
You need to implement stratified k-fold splitting for the BI team's training pipeline in Python without using external libraries. Implement a function stratified_kfold_splits(labels: List[int], k: int) -> List[Tuple[List[int], List[int]]] that returns k (train_indices, val_indices) pairs preserving class proportions approximately in each fold. Assume labels are integers for classes and dataset fits in memory. Describe complexity and limitations.
MediumTechnical
65 practiced
Compare categorical encoding strategies for BI models: one-hot encoding, target/mean encoding, frequency encoding, ordinal encoding, and learned embeddings. Discuss how encoding choice affects hyperparameter tuning, model interpretability, and the risk of leakage (especially with target encoding).
EasyTechnical
86 practiced
Your classification dataset for fraud detection has 1% positive class. Before running expensive hyperparameter searches, list practical heuristics and quick experiments you would run (data-level and algorithm-level) to improve baseline performance and why they'd help for BI use cases.
EasyTechnical
77 practiced
Explain the bias-variance trade-off and how it informs selecting model complexity for a BI dashboard. Provide a concrete example where increasing complexity improved training accuracy but made the dashboard less useful (e.g., unstable predictions across weekly reports), and describe diagnostic steps and fixes.

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