What’s a Linear Relationship?

A linear relationship is a statistical term that describes the relationship between two variables that can be represented by a straight line when graphed. In a linear relationship, changes in one variable cause changes in the other.

Linear relationships can be represented graphically or mathematically:
Graphical representation
A straight line connects the variables and constant on a graph. The line can increase, decrease, or remain constant.

Mathematical representation
The equation y = mx + b is used to represent a linear relationship.

Linear relationships are common in everyday life and in healthcare. For example, a teacher might observe a linear relationship between the scores on two spelling tests given to her students.