Preacher, K. J., & Hayes, A. F. (2008). Asymptotic and resampling strategies for assessing and comparing indirect effects in multiple mediator models.Behavior Research Methods, 40, 879-891.
http://link.springer.com/article/10.3758%2FBRM.40.3.879
SEM(パス解析)とは異なるアイディア
SPSSで実行する
SPSS FAQ
How can I analyze multiple mediators in SPSS?
Cf.