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Key Technical Interview Questions for Data Science 2📊

Techniques to Prevent Overfitting in Decision Trees and Introduction to Random Forest and Ensemble Methods in Data Science [00:05](   • Key Technical Interview Questions for Data...  ) Pruning techniques help prevent decision tree overfitting. Pre-pruning stops tree growth early through constraints like maximum depth and minimum sample thresholds. Post-pruning grows the full tree first and then removes non-contributing branches to improve generalization. [00:20](   • Key Technical Interview Questions for Data...  ) Random forest reduces overfitting using bagging with multiple decision trees. CP and validation forms help minimize overfitting and enhance model generalization prior to using random forests. Random forest employs bootstrap aggregation to create diverse decision trees from random data subsets. [00:38](   • Key Technical Interview Questions for Data...  ) Random forests improve model performance by reducing variance and overfitting. Random forests utilize random subsets of features to introduce diversity, enhancing predictive accuracy. Key hyperparameters include n_jobs for parallel processing and max_features for controlling feature consideration per split. [00:54](   • Key Technical Interview Questions for Data...  ) Understanding bias-variance trade-off in machine learning. Bias is the error from overly simplistic model assumptions, leading to underfitting. Variance is the error from model sensitivity to small fluctuations in training data. [01:14](   • Key Technical Interview Questions for Data...  ) Understanding bias-variance tradeoff and ensemble methods in model evaluation. High variance models overfit, while simpler models like linear regression have high bias but low variance. Ensemble methods such as bagging and boosting help improve model performance by combining multiple models to reduce errors. [01:30](   • Key Technical Interview Questions for Data...  ) Aggregation techniques improve model performance by reducing variance. Random Forest employs bagging by training on random subsets to average predictions, mitigating overfitting. Boosting sequentially builds models to reduce errors, emphasizing misclassified instances to enhance accuracy. [01:49](   • Key Technical Interview Questions for Data...  ) Bagging and boosting utilize different learning processes for model training. Bagging employs parallel learners, aggregating individual model outputs to improve accuracy and reducing variance. Boosting uses sequential learners, refining predictions iteratively to minimize error and enhancing performance. [02:09](   • Key Technical Interview Questions for Data...  ) Comparing exhaustive versus randomized and vision cross-validation methods. Exhaustive cross-validation examines all permutations, ensuring thoroughness but demanding high computational resources. Randomized cross-validation samples a fixed number of combinations quickly, while vision cross-validation adapts sampling based on previous evaluations for efficiency Key Insights for [Key Technical Interview Questions for Data Science 2📊](   • Key Technical Interview Questions for Data...  ) by [Merlin AI](https://merlin.foyer.work/) *Understanding Random Forests* *Ensemble Learning:* Random forests utilize an ensemble method known as bagging (bootstrap aggregation), where multiple decision trees are built on various bootstrap subsets of the data. *Feature Subset Selection:* At each split, a random subset of features is considered, promoting diversity among trees, which helps in reducing variance and overfitting. *Key Hyperparameters:* Important parameters include the number of trees (n_estimators), the number of features considered at each split (max_features), and the minimum samples required at a leaf node (min_samples_split). *Bias-Variance Trade-Off* *Bias:* This refers to the error introduced by overly simplistic assumptions in the learning algorithm, which can lead to underfitting. High bias models, like linear regression, can miss complex patterns in data. *Variance:* Variance represents the error due to sensitivity to fluctuations in the training data, often causing overfitting in complex models, such as deep decision trees or neural networks. *Model Balance:* A good model seeks to balance bias and variance to minimize total error, recognizing that simpler models typically exhibit high bias and low variance, while complex models tend to have the opposite. *Ensemble Methods: Bagging vs. Boosting* *Bagging:* Short for bootstrap aggregation, this method reduces variance by training multiple models on random subsets of data with replacement and averaging their predictions. It operates in parallel, as seen in random forests. *Boosting:* This technique builds models sequentially, where each new model attempts to correct errors made by previous models. Misclassified instances