Definition:

A mediator variable is a third variable that comes between the independent variable and the dependent variable in a statistical or research model. It is used to explain the relationship or mechanism through which the independent variable influences the dependent variable.

Explanation:

Mediator variables help to understand the underlying process by which the independent variable affects the dependent variable. They are considered to be part of the causal pathway between the independent and dependent variables. The presence of a mediator variable suggests that the relationship between the independent and dependent variables is not direct, but rather indirect through the mediator.

Role:

The mediator variable plays a crucial role in establishing a cause-and-effect relationship. It helps to explain why and how changes in the independent variable lead to changes in the dependent variable. By identifying and examining the mediator variable, researchers gain insights into the underlying mechanisms of a relationship.

Example:

Let’s consider a study investigating the relationship between exercise and stress. The independent variable is the amount of physical exercise, the dependent variable is stress levels, and a potential mediator variable could be self-esteem. In this example, self-esteem acts as a mediator variable between exercise and stress. The study might find that increased levels of exercise lead to higher self-esteem, which in turn lowers stress levels.