# Total indirect effects: Structural equation modeling

I'm trying to calculate the total indirect effects in a structural equation model with four exogenous latent variables, four latent mediators, and one outcome variable. Mplus gives the option for the "sum of indirect effects", but I'm not sure how to get this information in 'lavaan'. I found a paper that reported the sum of indirect effects from 'lavaan', but I'm not sure how to run this analysis.

In Lavaan you can calculate new parameters, using the := operator.

Use this to calculate the sum of indirect effects. Here's an example. We have 4 predictors (x1-x4), one mediator (m) and one outcome (y).

m ~ x1 (mx1)
m ~ x2 (mx2)
m ~ x3 (mx3)
m ~ x4 (mx4)

y ~ x1 (yx1)
y ~ x2 (yx2)
y ~ x3 (yx3)
y ~ x4 (yx4)

y ~ m

totIndEffect := yx1 + yx2 + yx3 + yx4

• So for total indirect effects, you can simply sum up the individual indirect effects for the dependent variables? Mar 29, 2016 at 17:02
• Yep, that's it. Mar 29, 2016 at 17:20
• Do you know of any references explaining more background about this? I was thinking of summing up direct and indirect effects within a path analysis and my co-authors are wondering if this is a legitimate thing to do. Jun 13, 2022 at 17:58
• Hmm... I don't know of a reference, but there must be one. Maybe ask a new question? Jun 13, 2022 at 23:12