Conceptual framework: Mediating variables
A mediating (or mediator) variable is an integral part of a cause-and-effect relationship. It makes it easier to understand how the independent variable is affecting the dependent variable and what is governing that relationship.
Mediating variables in a conceptual framework
This is a continuation of an article explaining how to build a conceptual framework. Our example framework maps the relationship between “hours of study” (independent variable) and “exam score” (dependent variable).
Now we’ll expand the framework by adding a mediating variable. In a cause-and-effect relationship, a mediating variable is a variable that links the independent and dependent variables, allowing the relationship between them to be better explained.
Mediating variables can be difficult to interpret, and care must be taken when conclusions are drawn from them. The complexity involved is beyond the scope of the article, so we won’t go into great detail. Instead, we’ll focus on helping you develop a basic understanding of what a mediating variable is and when it may need to be considered.
Here’s how the conceptual framework might look if a mediator variable were involved:
In this example, the relationship between the independent variable (“hours of study”) and the dependent variable (“exam score”) takes center stage: our hypothesis is that the more hours a student studies, the better they will do on the exam.
Now we add the mediating variable of “number of practice problems completed”, which comes between the independent and dependent variables. The hours of study impacts the number of practice problems, which in turn impacts the exam score.
The more hours a student studies, the more practice problems they will complete; the more practice problems completed, the higher the student’s exam score will be. By adding the mediating variable of “number of practice problems completed,” we help explain the cause-and-effect relationship between the two main variables.
Mediator vs moderator
It’s important not to confuse a mediator with a moderator. A moderating variable can impact the outcome of a dependent variable, but it is not affected by the independent variable.
For example, the variable “IQ” is a moderator, not a mediator: although IQ may impact the exam score (the dependent variable), the number of hours spent studying (the independent variable) does not affect IQ. No matter how many hours you study, your IQ will not increase.