I want to do a mediation analysis, with the following variables:
X: Independent variable: Categorical (2 levels) M: Mediator: Categorical (5 levels) Y: Dependent variable: Continuous
Following MacKinnon, Lockwood, Hoffman, West, & Sheets (2002), I need to perform 2 analysis:
- Regression analysis with X as independent and Y as dependent variable.
- Regression analysis with X and Y as independent variables and M as dependent variable.
A full mediation would mean:
The Regression weight X -> Y in the first analysis is significant
The Regression weight Y -> M in the second analysis is significant
The Regression weight X -> M in the second analysis is not significant
I have 3 questions:
- Is the above a (so not the) right thing to perform mediation analysis?
- Is my second analysis a multinomial logistic regression?
- Is my first analysis a GLM univariate?
For my analysis, I can only use SPSS 19 (without SEM).
Reference: MacKinnon, D.P., Lockwood, C.M., Hoffman, J.M., West, S,.G., & Sheets, V. (2002). A comparison of methods to test mediation and other intervening variable effects. Psychological Methods. 3, 309 - 327.