NPTEL Introduction to Machine Learning Week 7 Assignmeent Answers 2024

1. Define active learning:

A learning approach where the algorithm passively receives all training data at once
A technique where the model learns from its own predictions without human intervention
An iterative learning process where the model selects the most informative data points for labeling
A method where the model randomly selects data points for training to reduce bias

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2. Given 100 distinct data points, if you sample 100 times with replacement, what is the expected number of distinct points you will obtain?

Approximately 50
Approximately 63
Exactly 100
Approximately 37

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3. What is the key difference between bootstrapping and cross-validation?

Bootstrapping uses the entire dataset for training, while cross-validation splits the data into subsets
Cross-validation allows replacement, while bootstrapping does not
Bootstrapping creates multiple samples with replacement, while cross-validation creates subsets without replacement
Cross-validation is used for model selection, while bootstrapping is only used for uncertainty estimation

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4. Consider the following confusion matrix for a binary classification problem:

What are the precision, recall, and accuracy of this classifier?

Precision: 0.81, Recall: 0.85, Accuracy: 0.83
Precision: 0.85, Recall: 0.81, Accuracy: 0.85
Precision: 0.80, Recall: 0.85, Accuracy: 0.82
Precision: 0.85, Recall: 0.85, Accuracy: 0.80

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5. AUC for your newly trained model is 0.5. Is your model prediction completely random?

Yes
No
ROC curve is needed to derive this conclusion
Cannot be determined even with ROC

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6. You are building a model to detect cancer. Which metric will you prefer for evaluating your model?

Accuracy
Sensitivity
Specificity
MSE

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7. You have 2 binary classifiers A and B. A has accuracy=0% and B has accuracy=50%. Which classifier is more useful?

A
B
Both are good
Cannot say

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8. You have a special case where your data has 10 classes and is sorted according to target labels. You attempt 5-fold cross validation by selecting the folds sequentially. What can you say about your resulting model?