This slide summarizes Barron & Kenny’s (1986) causal steps for establishing mediation, which we have just discussed.
However, do all of the steps have to be met for there to be mediation? Certainly, Step 4 does not have to be met unless the expectation is for complete mediation. Moreover, Step 1 is not required, but a path from the initial variable to the outcome is implied if Steps 2 and 3 are met.
However, if c’ is opposite in sign to ab, then it could be the case that Step 1 is not met, but there is still mediation. In this case the mediator acts like a suppressor variable.
Statistics Training: Introduction to Path Analysis
1. What is Path Analysis?
- 2. A Quick Review of Regression
- 3. Moderation and Mediation Explained
- 4. Example of the Difference between Moderation and Mediation
- 5. Example of a Basic Test of Mediation
- 6. Mediation Analysis: Procedures and Tests
- 7. Causal Steps to Establish Mediation: Step 1
- 8. Causal Steps to Establish Mediation: Step 2
- 9. Causal Steps to Establish Mediation: Steps 3 and 4
- 10. Barron and Kenny’s (1986) Criteria for Mediation
- 11. An Example of a Mediator Acting as a Suppressor
12. Testing for Significant Mediation
- 13. Sobel’s Test of Significant Mediation