Covariance

Question 1

If scores for one variable change then the scores for the other variable also change in a predictable manner

What term is used to describe this?

Answer 1

High covariance

Question 2

Changes in one variable are not accompanied by a predictable change in the other variable

What term is used to describe this?

Answer 2

Low covariance

Question 3

What is covariance?

Answer 3

A measure of how much two variables vary together

Question 4

Low covariance is…?

Answer 4

Changes in one variable are not accompanied by a predictable change in the other variable

Question 5

High covariance is…?

Answer 5

If scores for one variable change then the scores for the other variable also change in a predictable manner

Question 6

What is the formula for total covariance?

Answer 6

(x coordinate - mean of x variable) x (y coordinate - mean of y variable)

Repeat this depending on how ever many coordinates there are

And add all of the results together

Question 7

What is the formula for sample covariance?

Answer 7

Total covariance / (sample size - 1)

Question 8

What describes how much two variables (x, y) co-vary (the amount of variance they share)?

Answer 8

Sample covariance

Question 9

What is positive covariance?

Answer 9

Indicates that higher-than-average values of one variable tend to be paired with higher-than-average values of the other variable.

Question 10

What is negative covariance?

Answer 10

Indicates that higher-than-average values of one variable tend to be paired with lower-than-average values of the other variable.

Question 11

What is zero covariance?

Answer 11

If the two random variables are independent, the covariance will be zero. (However, a covariance of zero does not necessarily mean that the variables are independent. A nonlinear relationship can exist that still would result in a covariance value of zero.)

Question 12

Indicates that higher-than-average values of one variable tend to be paired with lower-than-average values of the other variable.

This is known as…?

Answer 12

Negative covariance

Question 13

Indicates that higher-than-average values of one variable tend to be paired with higher-than-average values of the other variable.

This is known as…?

Answer 13

Positive covariance

Question 14

If the two random variables are independent, the covariance will be zero. (However, a covariance of zero does not necessarily mean that the variables are independent. A nonlinear relationship can exist that still would result in a covariance value of zero.)

This is known as…?

Answer 14

Zero covariance

Question 15

How do you find the variance when you’re given only the s.d.?

Answer 15

Square the s.d.

Question 16

What is the formula for variance?

Answer 16

(x coordinate - mean of x variable) ^2 / (sample size -1)

Question 17

Data are collected for three participants on two variables (X, Y). The data are described below:

P1: (1, 3)

P2: (2, 4)

P3: (3, 5)

a) The mean for variable X is:

b) The mean for variable Y is:

c) The sample covariance of the X and Y data is:

Answer 17

a) 2.0
b) 4.0
c) 1.0

Question 18

Data are collected for three participants on two variables (X, Y). The data are described below:

P1: (2, 6)

P2: (4, 8)

P3: (6, 10)

a) The mean for variable X is:

b) The mean for variable Y is:

c) The sample covariance of the X and Y data is:

Answer 18

a) 4.0
b) 8.0
c) 4.0