How do manipulation checks interfere with the inference of causal relationships?

Area of Science:

• Psychology
• Quantitative Psychology
• Experimental Design

Background:

• Mediation analyses are common in experimental psychology.
• Manipulation checks are frequently used to validate experimental manipulations.
• The performance of mediation analyses with manipulation checks requires further investigation.

Purpose of the Study:

• To investigate the performance of mediation analyses that include manipulation check variables.
• To assess the validity of using manipulation checks in experimental studies.
• To examine the impact of manipulation intensity and measurement error on mediation analysis results.

Main Methods:

• Simulated data were used to model varying levels of manipulation intensity.
• Measurement error in the manipulation check variable was systematically varied.
• Mediation analyses were conducted under different simulation conditions.

Main Results:

• Unstable path coefficients and standard errors were observed when manipulation was successful and measurement error was low.
• Inconsistent mediation situations were frequently detected under these conditions.
• When manipulation intensity was low and measurement error was low, the indirect effect validated the manipulation.

Conclusions:

• The use of manipulation checks in mediation analyses requires careful consideration of manipulation success and measurement error.
• Findings suggest that under certain conditions, mediation analyses with manipulation checks may yield unreliable results.
• Recommendations are provided for the appropriate use of manipulation checks in experimental research to ensure valid findings.