Correlation

Scatter Plot and Correlation

1. Scatter Plot
   A scatter plot represents the ordered pairs of two variables and on a coordinate plane. This plot is called a scatter plot of the variables and .
2. Correlation
   If there is a tendency for one variable to change as another variable changes, this relationship is called a correlation, and it is said that there is a correlation between the two variables and .
   • Positive Correlation: When the value of one variable increases, the value of the other variable also tends to increase.
   • Negative Correlation: When the value of one variable increases, the value of the other variable tends to decrease.

• In a scatter plot with either a positive or negative correlation, the closer the points are to forming a straight line, the stronger the correlation. The more spread out the points are, the weaker the correlation. In the following diagrams, (1) shows a stronger correlation than (2), and (3) shows a stronger correlation than (4).

(1) Positive Correlation	(2) Positive Correlation	(3) Negative Correlation	(4) Negative Correlation

• On the other hand, if the relationship between and is unclear, meaning it’s not obvious whether increases or decreases as increases, there is said to be no correlation between and , as shown in the diagrams below.