CS365: Artificial Intelligence

Department of Computer Science & Engineering, IIT Kanpur

Jan - Apr 2015

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Homework 1

Overfitting and Complex Models

What to do

You are given four files: These files contain data in two columns: "Time" and "Height". This data represents height measurements for dropping a ball down for a fixed amount of time.

What to submit

In each of cases below, you should plot a graph for each of these models to demonstrate, visually, how well the curve fits the data. Provide a graph of Error vs. Polynomial Degree for both (small and big) datasets.

A. Use the h1_train_small.csv file to train polynomials of degrees N= 0, 1, 2, 3, 5, and 9 (minimally). You should plot the accuracy on the training set and compare it with that on the h1_test.csv test data. Also tabulate the coefficients of your polynomials for these different N (as in Table 1.1 from Bishop, page 8).

B. You will then use the h1_validate.csv validation dataset and plot the error on this for the different polynomials. You should report the optimal degree N as suggested by the validation, and the final error, tested on the h1_test.csv test data, for your optimal model.

C. You will now use the larger training set h1_train_big dataset, and observe the differences with the test set results. What N is suggested now by the training set? Is there any benefit to using a validation set in this case?

Finally, analyze why you are getting the results you have. What is your best guess for the target function (which is, of course, a quadratic)? What is the difference between Test data and Validation data?

Provide all the code you have used for every step in the assignment.

Submission Process

Submissions should be through your course webpage:
home.iitk.ac.in/~USERID/cs365/hw1/index.html
This hw1/ directory should contain all images etc. related to this assignment.

NOTE: Please do not use global references e.g. <a href="home.iitk.ac.in/~USERID/cs365/FILE">). Instead use local paths ( <a href="FILE">).

Due date:

Jan 16, Friday, 23.59 pm. Code should be uploaded by Sunday 18th.