Hello,

This is Elaine.

I am trying a path analysis using lavaan Package.

There are three explanatory variables: X, Z, and M.
The response variable is Y.
A, b, and c have direct effects on Y.

On the other hand, X and Z also have direct effects on M.
In other words, X and Z have indirect effects on Y.

I found the code example of lavaan package describes only one indirect
effect as below.
Please kindly advise how to modify it as two indirect effects.
Thank you.

Elaine

>  set.seed(1234)
>  X  <-  rnorm(100)
>  M  <-  0.5*X  +  rnorm(100)
>  Y  <-  0.7*M  +  rnorm(100)
>  Data  <-  data.frame(X  = X,  Y  =  Y,  M  =  M)
>  model  <-  '  #  direct  effect
+ Y  ~  c*X
+ #  mediator
+ M  ~  a*X
+ Y  ~  b*M
+ #  indirect  effect  (a*b)
+ ab  :=  a*b
+ #  total  effect
+ total  :=  c  +  (a*b)
+ '
>  fit  <-  sem(model,  data=Data)
>  summary(fit)

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