InterviewStack.io LogoInterviewStack.io

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.

EasyTechnical
0 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.
HardTechnical
0 practiced
Implement a successive halving scheduler in Python. The function should accept: a list of hyperparameter configs, a max_resource (e.g., max epochs), an eval_fn(config, resource) returning a scalar metric (higher is better), and should iteratively allocate resources, evaluate, promote top performers, and return the best config. Focus on correctness and clarity (you may assume synchronous evaluation). Describe complexity and limitations.
HardTechnical
0 practiced
Provide pseudocode or a Python-like outline for nested cross-validation that includes hyperparameter selection in the inner loop and performance estimation in the outer loop. Highlight common pitfalls (data leakage through preprocessing, incorrect refitting, reporting inner-loop scores instead of outer estimates) and the correct steps to obtain an unbiased performance estimate and a deployable final model.
MediumTechnical
0 practiced
Describe how to design a hyperparameter search space: choosing discrete vs continuous ranges, when to sample uniformly vs logarithmically (log-uniform), how to handle conditional or hierarchical parameters (e.g., 'max_depth' only relevant when using trees), and strategies to constrain/shape the space to reduce wasted evaluations for BI workloads.
MediumTechnical
0 practiced
Explain how max_depth, min_child_weight (or min_data_in_leaf), subsample, colsample_bytree, and learning_rate interact when tuning a gradient boosting model. Propose a practical order for tuning these hyperparameters for a BI team doing a first-pass search given compute and interpretability constraints.

Unlock Full Question Bank

Get access to hundreds of Model Selection and Hyperparameter Tuning interview questions and detailed answers.

Sign in to Continue

Join thousands of developers preparing for their dream job.