QUIZ 2.5, 3.5, 12

Question 1

A ________ ______ explores the possible relationship between two numerical variables by plotting the values of one numerical variable on the horizontal axis and the values of the second numerical variable on the vertical axis.

Answer 1

Scatter Plot

Question 2

What does a positive slope of a line through the points on a scatterplot tell us about the two variables?

Answer 2

That there is a strong increasing relationship between the 2 variables.

As X increases, Y generally increases.

Question 3

What does a negative slope of a line through the points of a scatter plot tell us about the relationship of two variables?

Answer 3

That as X values increase, the Y-values generally decrease.

The variables generally have a decreasing negative relationship.

Question 4

How is a variable plotted over time?

Answer 4

By using a time-series plot

Question 5

What is the measure of the strength of the linear relationship between two numerical variables (X & Y)?

Answer 5

Covariance

Question 6

What is the major flaw in using the covariance?

Answer 6

Covariance can have any value. it cannot be used to determine the RELATIVE STRENGTH of the relationship between X and Y.

Question 7

_______ of __________ measures the relative strength of the relationship between X and Y.

Answer 7

Coefficient of Correlation

Question 8

What is the value range of the Coefficient of Correlation?

Answer 8

+1 to -1

Question 9

What does a coefficient of correlation measured at +1 mean?

Answer 9

The relationship between X and Y is PERFECTLY POSITIVE.

Question 10

What does a coefficient of correlation measurement of -1 indicate?

Answer 10

The relationship between X and Y is PERFECTLY NEGATIVE

Question 11

What is the measure of the coefficient of correlation if there is no relationship between X and Y?

Answer 11

= 0

Question 12

What is the Greek symbol used to represent the coefficient of correlation?

Answer 12

Rho