16 questions pulled from past papers whose wording matches this week's topics, newest first, duplicates removed. Pick your answers, then press Check answers. Figures and answer keys are the originals.
In the context of bagging, consider a dataset of size . A bag is a set of points that is obtained by sampling uniformly at random from the dataset with replacement. Which of the following represents the probability that a data-point is not a part of the bag?
In a random forest classifier with total features, each split is chosen by evaluating a randomly selected subset of features. Consider how changing affects the behavior of the forest. Which of the following statements are correct?
Increasing reduces the correlation between any two trees in the forest.
Decreasing reduces the correlation between any two trees in the forest.
If is too small, individual trees may underfit the data.
Increasing always decreases the variance of the random forest model.
Decreasing makes trees more similar to each other.
Consider the following one-dimensional dataset with binary labels .
AdaBoost uses decision stumps as weak learners. Assume the initial distribution of the dataset assigns equal weights to all data points, i.e.,
, for . At iteration , AdaBoost chooses the decision stump
Based on the above data, answer the given subquestions.
After AdaBoost updates the sample weights for iteration , which pair of points will have the smallest (and equal) weights while training the second stump ?
Match the characteristics given below with the appropriate ensemble technique. 1. Decision stumps 2. Deep decision trees 3. Parallel execution 4. Sequential execution
Consider the following two-dimensional dataset with two classes: +1 for blue points and -1 for red points. An AdaBoost algorithm was run on this dataset using decision stumps as weak learners.
Consider the following two-dimensional dataset with two classes: +1 for blue points and -1 for red points. An AdaBoost algorithm was run on this dataset using decision stumps as weak learners. To train the second decision stump, which pair of points will be assigned equal weights to create the training data-set?
Overfitting models have high bias and low variance.
Underfitting models have low bias and high variance.
Generally, weak learners in the random forest tend to overfit.
If the performance of each estimator in the bagging algorithm is almostidentical, the benefit of using bagging to combine them may be minimal or insignificant.
In random forests, multiple decision trees (estimators) are trainedsimultaneously, allowing for parallel processing and faster model training.
If the performance of each estimator in the bagging algorithm is almostidentical, the benefit of using bagging to combine them may be minimal or insignificant.
Weak learners have low bias and high variance.
In random forests, multiple decision trees (estimators) are trainedsimultaneously, allowing for parallel processing and faster model training.
In the random forest algorithm, multiple decision trees are trained on thesame dataset to create an ensemble model.
In a random forest model let p < m be the number of randomly selected features that are used to identify the best split at any node of a tree. Which of the following are true? (m is the original number of features)
Increasing p reduces the correlation between any two trees in the forest.
Decreasing p reduces the correlation between any two trees in the forest.
Increasing p increases the performance of individual trees in the forest.
Decreasing p increases the performance of individual trees in the forest.