Schoemann et al. created an easy to use web app that allows you to use Monte Carlo simulation to calculate sample size based on target power for the following models:
- simple mediation
- two parallel mediators
- two serial mediators
Access the web app here: https://schoemanna.shinyapps.io/mc_power_med
Citation
Schoemann, A. M., Boulton, A. J., & Short, S. D. (2017). Determining power and sample size for simple and complex mediation models. Social Psychological and Personality Science, 8(4), 379-386. https://doi.org/10.1177/1948550617715068