Conceptualizing and testing random indirect effects and moderated mediation in multilevel models: new procedures and recommendations
Psychological Methods (2006) - Comment
pubmed: 16784335  doi: 10.1037/1082-989x.11.2.142  issn: 1082-989x  issn: 1939-1463 

Daniel J. Bauer, Kristopher J. Preacher, Karen M. Gil