Correlation between Two Variables

Question 1

What is a “Scatter Plot”?

Answer 1

A two-dimensional graphical plot of paired observations of values for the independent and dependent variables in a simple linear regression.

Question 2

What is “Correlation”?

Answer 2

A measure of the linear relationship between two random variables.

Question 3

What is “Sample covariance”?

Answer 3

A measure of how to variables in a sample move together.

Question 4

What is a “sample correlation coefficient”?

Answer 4

A standardized measure of how to variables in a sample move together. It is the ratio of the sample covariance to the product of the two variables’ standard deviations.

Question 5

What is spurious correlation?

Answer 5

Refers to:
(1) Correlation between two variables that reflects chance relationships in a particular dataset;

(2) Correlation induced by a calculation that mixes each of two variables with a third variable; and

(3) Correlation between two variables arising not from a direct relation between them but from their relation to a third variable.