**Mediation vs. Moderation**

It’s easy
to confuse the two. They sound similar, and while they both look at how a third
variable fits into a relationship of interest, they are **not the same.** Let’s
break it all down. In this post, we will highlight some key characteristics of
mediation and moderation. We will also talk about some of the key differences
between these analyses.

**Mediation**

A
mediation analysis is an extension of multiple regression. We start to think
about mediation when we want to **explain** why or how *X *affects *Y*.
This tells us more information about **how or why** an independent variable
affects a dependent variable. The relationship between *X *and *Y *is
the **total effect**.

In
mediation, we add an independent variable called the **mediator**. Mediators **mediate** the relationship between *X *and *Y*. This occurs by *X *affecting *M* leading to *M *affecting *Y,* which is called
the **indirect effect**. The **direct effect** is the relationship between *X *and *Y *in the presence of a mediator. Mediation occurs when (1)
there is a statistically significant indirect effect (2) the direct effect is
smaller than the total effect.

**Moderation**

Moderation
analyses look at **interactions**. In other words, we’re interested in
whether the effect of *X *on *Y *varies **depending** on another
variable (i.e., the moderator).

Moderator
variables **modify** the relationship between *X *and *Y*. They
affect the **strength and direction** of the relationship between *X *and *Y*. That means that *X*‘s effect on *Y *can change **depending** on the moderator.

An **interaction** or **product term** represents the moderator effect. We can calculate the
interaction term by multiplying the independent variable by the moderator (*X***W*).

**Key Differences**

Mediators
are **possible explanations** for a relationship between *X *and *Y*.
Moderators **affect the magnitude** of the effect of *X *on *Y*.
Another difference is in the relationship that mediators and moderators have
with the independent variable. In theory, mediators result from the independent
variable (i.e., *X *→ *M*). On the other hand, there is **no
directional relationship **assumed between X and a moderator (i.e., *X *↔ *M*).

Overall, we use mediation analyses to **explain** relationships. We use moderation analyses to understand what variables **affect the strength and direction** of a relationship.

**Sources**

- Baron, R., & Kenny, D. (1986). The moderator-mediator variable distinction in social psychological research: Conceptual, strategic, and statistical considerations. Journal of Personality and Social Psychology, 51, 1173-1182.
- Giannoulis C. (2020). To moderate or to mediate? Retrieved from https://www.theanalysisfactor.com/to-moderate-or-to-mediate/
- James Gaskin (2018, February 05). Mediator or moderator? [Video file]. Retrieved from https://www.youtube.com/watch?v=WZr1jlKi_s0
- Statistics Soluitions (2020). What is the difference between moderation and mediation? Retrieved from https://www.statisticssolutions.com/what-is-the-difference-between-moderation-and-mediation/
- University of Wisconsin-Madison (1999). Mediator versus moderator variables. Retreived from https://psych.wisc.edu/henriques/mediator.html