Data Principles week 8 part 2

What does the mean value of an attribute in a dataset represent?

• The sum of all the values of the attribute

• The expected value of the attribute

• The difference between the highest and lowest value of the attribute

• The product of all the values of the attribute

How is the covariance between two attributes A and B defined?

• Cov(A, B) = E((A - Ā)(B - B̄))

• Cov(A, B) = E(A + B) - ĀB̄

• Cov(A, B) = E(A/B) - Ā/B̄

• Cov(A, B) = E(A - B) - Ā - B̄

Which of the following is a simplified computation of covariance?

• Cov(A, B) = E(A + B) - ĀB̄

• Cov(A, B) = E(A · B) - ĀB̄

• Cov(A, B) = E(A/B) - Ā/B̄

• Cov(A, B) = E(A - B) - Ā - B̄

What does a negative covariance between two variables A and B indicate?

• A and B tend to move in the same direction

• A and B are independent

• A and B tend to move in opposite directions

• The relationship between A and B cannot be determined

What can be inferred if the covariance between two variables A and B is zero?

• A and B tend to move in the same direction

• A and B tend to move in opposite directions

• A and B are independent

• A non-linear relationship can exist that still would result in a covariance value of zero

When two variables A and B have a positive covariance, what is their relationship?

• A and B are independent

• A and B tend to move in opposite directions

• A and B tend to move in the same direction

• The relationship between A and B cannot be determined

What is the expected value (E) of the stock prices for AllElectronics?

• $4

• $10.8

• $7

• $20

What is the expected value (E) of the stock prices for HighTech?

• $4

• $10.8

• $7

• $20

What is the covariance (Cov) between AllElectronics and HighTech stock prices?

• 50.2

• 43.2

• 7

• 4

If Cov(AllElectronics, HighTech) > 0, what does it imply about the stock prices of both companies?

• The stock prices for both companies rise together.

• The stock prices for both companies fall together.

• The stock prices for one company rise while the other falls.

• There is no relationship between the stock prices of the companies.