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Question 1

Here is a table of 1-5 star ratings for five movies (M, N, P. Q. R) by three raters (A, B, C).

	M	N	P	Q	R
A	1	2	3	4	5
B	2	3	2	5	3
C	5	5	5	3	2

Normalize the ratings by subtracting the average for each row and then subtracting the average for each column in the resulting table. Then, identify the true statement about the normalized table.

The largest element is (C,M).

There are more -1's than 0's.

The smallest element is (C,R).

The smallest element is (B,P).

Question 2

Below is a table giving the profile of three items.

A	1	0	1	0	1	2
B	1	1	0	0	1	6
C	0	1	0	1	0	2

The first five attributes are Boolean, and the last is an integer "rating." Assume that the scale factor for the rating is α. Compute, as a function of α, the cosine distances between each pair of profiles. For each of α = 0, 0.5, 1, and 2, determine the cosine of the angle between each pair of vectors. Which of the following is FALSE?

For α = 1, A is closer to B than C is.

For α = 2, B is closer to A than C is.

For α = 1, C is closer to B than A is.

For α = 0.5, B is closer to C than A is.

In accordance with the Coursera Honor Code, I (Anonymous Student) certify that the answers here are my own work.

You cannot submit your work until you agree to the Honor Code. Thanks!

Mining Massive Datasets

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by Jure Leskovec, Anand Rajaraman, Jeff Ullman

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Mining Massive Datasetsby Jure Leskovec, Anand Rajaraman, Jeff Ullman

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Mining Massive Datasets
by Jure Leskovec, Anand Rajaraman, Jeff Ullman