Introduction to Machine Learning Week 2 NPTEL Assignment Answers 2025

NPTEL Introduction to Machine Learning Week 2 Assignment Answers 2025

1. In a linear regression model y=θ01x12x2+…+θpxp, what is the purpose of adding an intercept term (θ0)?

  • To increase the model’s complexity
  • To account for the effect of independent variables.
  • To adjust for the baseline level of the dependent variable when all predictors are zero.
  • To ensure the coefficients of the model are unbiased.
Answer :- c

2. Which of the following is true about the cost function (objective function) used in linear regression?

  • It is non-convex.
  • It is always minimized at θ = 0.
  • It measures the sum of squared differences between predicted and actual values.
  • It assumes the dependent variable is categorical.
Answer :- c

3. Which of these would most likely indicate that Lasso regression is a better choice than Ridge regression?

  • All features are equally important
  • Features are highly correlated
  • Most features have small but non-zero impact
  • Only a few features are truly relevant
Answer :- d

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4. Which of the following conditions must hold for the least squares estimator in linear regression to be unbiased?

  • The independent variables must be normally distributed.
  • The relationship between predictors and the response must be non-linear.
  • The errors must have a mean of zero.
  • The sample size must be larger than the number of predictors.
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5. When performing linear regression, which of the following is most likely to cause overfitting?

  • Adding too many regularization terms.
  • Including irrelevant predictors in the model.
  • Increasing the sample size.
  • Using a smaller design matrix.
Answer :- 

6. You have trained a complex regression model on a dataset. To reduce its complexity, you decide to apply Ridge regression, using a regularization parameterλ. How does the relationship between bias and variance change asλ becomes very large? Select the correct option

  • bias is low, variance is low.
  • bias is low, variance is high.
  • bias is high, variance is low.
  • bias is high, variance is high.
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7. Given a training data set of 10,000 instances, with each input instance having 12 dimensions and each output instance having 3 dimensions, the dimensions of the design matrix used in applying linear regression to this data is

  • 10000 × 12
  • 10003 × 12
  • 10000 × 13
  • 10000 × 15
Answer :- 

8. The linear regression model y=a0+a1x1+a2x2+…+apxp is to be fitted to a set of N training data points having P attributes each. Let X be N x (p+1) vectors of input values (augmented by 1‘s), Y be N x 1 vector of target values, and θ be (p+1)×1 vector of parameter values (a0,a1,a2,…,ap). If the sum squared error is minimized for obtaining the optimal regression model, which of the following equation holds?

  • XTX = XY
  • Xθ = XTY
  • XTXθ = Y
  • XTXθ = XTY
Answer :- 

9. Which of the following scenarios is most appropriate for using Partial Least Squares (PLS) regression instead of ordinary least squares (OLS)?

  • When the predictors are uncorrelated and the number of samples is much larger than the number of predictors.
  • When there is significant multicollinearity among predictors or the number of predictors exceeds the number of samples.
  • When the response variable is categorical and the predictors are highly non-linear.
  • When the primary goal is to interpret the relationship between predictors and response, rather than prediction accuracy.
Answer :- 

10. Consider forward selection, backward selection and best subset selection with respect to the same data set. Which of the following is true?

  • Best subset selection can be computationally more expensive than forward selection
  • Forward selection and backward selection always lead to the same result
  • Best subset selection can be computationally less expensive than backward selection
  • Best subset selection and forward selection are computationally equally expensive
  • Both (b) and (d)
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