Mediation: The Four Steps David A. Kenny davidakenny.net

2 Mediation Webinar Basics

3 The Beginning Model

4 The Mediational Model

5 The Four Paths X  Y: path c X  M: path a M  Y (controlling for X): path b X  Y (controlling for M): path c ′ (standardized or unstandardized)

6 In the 1980s Different Researchers Proposed a Series of Steps to Test Mediation Judd & Kenny (1981) James & Brett (1984) Baron & Kenny (1986)

7 Steps Step 1: X  Y (test path c) Step 2: X  M (test path a) Step 3: M (and X)  Y (test path b) Step 4: X (and M)  Y (test path c ′ )

8 Differences in the Three Approaches James & Brett assuming complete mediation estimate Step 3 without controlling for X whereas both Judd & Kenny and Baron & Kenny control for X. Judd & Kenny and James & Brett require all four steps whereas Baron & Kenny do not require Step 4.

9 Steps Incredibly Popular with Practitioners Suggested a straightforward way of testing mediation using a widely available estimating method. Very often lead to a successful result: Some sort of mediation was indicated. Very widely adopted and eventually the expectation was for some sort of mediational analysis. 9

10 References Judd, C. M., & Kenny, D. A. (1981). Process analysis: Estimating mediation in treatment evaluations. Evaluation Review, 5, James, L. R., & Brett, J. M. (1984). Mediators, moderators and tests for mediation. Journal of Applied Psychology, 69, Baron, R. M., & Kenny, D. A. (1986). The moderator-mediator variable distinction in social psychological research: Conceptual, strategic and statistical considerations. Journal of Personality and Social Psychology, 51,

11 More Mediation Webinars Indirect Effect Testing the Indirect Effect Causal Assumptions