All examples for Mediation & Moderation Analysis Guide

Simple Mediation: Self-Efficacy Mediating Training Effects

Demonstrates PROCESS Model 4 for testing whether self-efficacy mediates the relationship between training and job performance, with complete SPSS/R/Python code and APA reporting template.

Input

What you provide to the skill

Does self-efficacy mediate the effect of training on job performance?

Output

What the skill generates for you

Mediation Analysis Report

Research Question Classification

Question: Does self-efficacy mediate the effect of training on job performance?

Analysis Type: Simple Mediation (PROCESS Model 4)

Rationale: This is a mediation question because it asks whether self-efficacy EXPLAINS or TRANSMITS the effect of training on job performance. The question asks “how” training affects performance (via self-efficacy), not “when” or “for whom.”


Conceptual Path Diagram

Self-Efficacy (M)
↗ ↘
a b
↗ ↘
Training (X) ──c'──→ Job Performance (Y)
Path a: Training → Self-Efficacy
Path b: Self-Efficacy → Job Performance (controlling for Training)
Path c': Direct effect of Training on Job Performance (after accounting for M)
Indirect effect: a × b (effect transmitted through Self-Efficacy)
Total effect: c = c' + (a × b)

PROCESS Model Selection

Model 4 - Simple Mediation

This is the appropriate model because:

  • One independent variable (Training)
  • One mediator (Self-Efficacy)
  • One dependent variable (Job Performance)
  • No moderators specified
  • Testing whether self-efficacy explains the training-performance link

Runnable Code

SPSS PROCESS Macro

PROCESS y=JobPerformance /x=Training /m=SelfEfficacy /model=4
/boot=5000 /conf=95.

R (mediation package)

library(mediation)
# Fit mediator model (a path)
med_model <- lm(SelfEfficacy ~ Training, data = df)
# Fit outcome model (b and c' paths)
out_model <- lm(JobPerformance ~ Training + SelfEfficacy, data = df)
# Run mediation analysis with bootstrapping
med_result <- mediate(med_model, out_model,
treat = "Training", mediator = "SelfEfficacy",
boot = TRUE, sims = 5000)
# View results
summary(med_result)

Python (pingouin)

import pingouin as pg
import pandas as pd
result = pg.mediation_analysis(
data=df,
x='Training',
m='SelfEfficacy',
y='JobPerformance',
n_boot=5000,
seed=42
)
print(result)

How to Interpret Results

Critical Effects to Examine

Effect Path What It Tests Significance Criterion
Path a Training → Self-Efficacy Does training increase self-efficacy? p < .05
Path b Self-Efficacy → Job Performance Does self-efficacy predict performance (controlling for training)? p < .05
Direct effect (c’) Training → Job Performance Does training predict performance after accounting for self-efficacy? p < .05 (not required for mediation)
Indirect effect (a×b) Training → Self-Efficacy → Job Performance KEY TEST: Is the effect transmitted through self-efficacy? Bootstrap 95% CI excludes zero
Total effect (c) Training → Job Performance Overall relationship before considering mediator p < .05

Decision Rules

Mediation is supported if:

  • Bootstrap 95% CI for the indirect effect (a×b) does NOT include zero
  • Example: CI [0.12, 0.38] → Significant mediation
  • Example: CI [-0.05, 0.25] → No significant mediation

Type of mediation:

  • Partial mediation: Indirect effect is significant AND direct effect (c’) is significant
  • Full mediation: Indirect effect is significant AND direct effect (c’) is non-significant
    • Note: Modern practice avoids “full mediation” terminology; report both effects

APA-Formatted Results Section

To test whether self-efficacy mediated the relationship between training
and job performance, we conducted a mediation analysis using PROCESS Model 4
(Hayes, 2022) with 5,000 bootstrap samples.
Results indicated that training significantly predicted self-efficacy
(a = [INSERT COEF], SE = [INSERT SE], t = [INSERT t], p = [INSERT p]).
Self-efficacy significantly predicted job performance controlling for
training (b = [INSERT COEF], SE = [INSERT SE], t = [INSERT t], p = [INSERT p]).
The direct effect of training on job performance remained significant
(c' = [INSERT COEF], SE = [INSERT SE], t = [INSERT t], p = [INSERT p]).
Critically, the indirect effect of training on job performance through
self-efficacy was significant (ab = [INSERT COEF], 95% CI [[INSERT LL],
[INSERT UL]]), supporting partial mediation. The indirect effect accounted
for approximately [INSERT %]% of the total effect of training on job
performance.

Common Pitfalls to Avoid

  1. DON’T use p-values for the indirect effect → Use bootstrap CI only
  2. DON’T claim causality with cross-sectional data → State limitations clearly
  3. DON’T say “fully mediated” if c’ is significant → Partial mediation is valid and common
  4. DON’T forget to report all path coefficients → Include non-significant paths

Reference

Hayes, A. F. (2022). Introduction to mediation, moderation, and conditional process analysis: A regression-based approach (3rd ed.). Guilford Press.