*! version 1.0 05Dec2015

help vaf

Title

vaf -- VAF in mediation models with SEM

A simple mediation model will include the following links:
INDEPENDENT->MEDIATOR->DEPENDENT
INDEPENDENT->DEPENDENT

Description

vaf computes the magnitude of the indirect effect in relation
to the total effect. That is, vaf computes the proportion of
the variance of a dependent variable explained by an independent
variable indirectly via a mediator variable/s. This means that the
mediator/s variable absorbs some of the direct effect between the
independent and dependent variable. The amount of indirect
effect determines whether no/partial/full mediation takes place.

VAF < 20% indicates (almost) no mediation

20% < VAF > 80% indicates partial mediation

VAF > 80% indicates (almost) full mediation

KW: mediation
KW: indirect
KW: effect
KW: SEM
KW: variance

Examples

. use http://www.stata-press.com/data/r14/sem_sm2.dta, clear

. qui sem (Alien67->anomia67 pwless67)(Alien71->anomia71 pwless71)(SES->educ66 occstat66)(Alien67<-SES)(Alien71<-Alien67 SES)

. vaf

. qui sem (F1->educ66 occstat66)(F2->anomia66 pwless66)(F3->anomia67 pwless67)(F4->anomia71 pwless71)(F2 F3<-F1)(F4<-F1 F2 F3)

. vaf

. qui sem (F1->educ66 occstat66)(F2->anomia66 pwless66)(F3->anomia67 pwless67)(F4->anomia71 pwless71)(F3<-F1 F2)(F4<-F1 F2 F3)

. vaf

Author

Mehmet Mehmetoglu
Department of Psychology
Norwegian University of Science and Technology
mehmetm@svt.ntnu.no

References

Hair, J. F., Hult, G. T. M., Ringle, C. M., & Sarstedt, M. (2013).
A PRIMER ON PARTIAL LEAST SQUARES STRUCTURAL EQUATION MODELING
(PLS-SEM). London: Sage.