SEM with three IVs, one mediation, and two DVs

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Mehrnoush Sarafan

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Dec 11, 2016, 2:25:36 PM12/11/16
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Hi,

I'm relatively new to R and the lavaan package so excuse me if some of the questions sound very basic. I'm trying to fit a structural equation model to my experimental data. I have three IVs (all categorical with two levels:0,1), some control variables - age, gender, work experience, industry- (all categorical), one mediator (measured using three items on 7-point Likert scale) and two dependent variables (both measured using three items on 7-point Likert scale).
I need to do conformity factor analysis for the three measured variables as well as mediation analysis to fit the model. Here is my syntax for only one of the DVs and without considering control variables. I was wondering whether this is the right way of do the analysis? how I can add my control variables? and is it possible to have two DVs?

SEM.model.buffering <- '
#measurement model 
Blame =~ Q1a + Q1b + Q1c
Buffering =~ Q2a + Q2b + Q2c
#direct effects
Buffering ~ s*Severity + r*Relational_Norms + c*Controllability + b*Blame
#mediator
Blame ~ sb*Severity + rb*Relational_Norms + cb* Controllability

# indirect effect
sbb := sb*b
rbb:= rb*b
cbb:= cb*b
# total effect
total := s + (sb*b) + r + (rb*b) + c + (cb*b)'

fit <- sem(SEM.model.buffering, data=Data)

Terrence Jorgensen

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Dec 12, 2016, 6:35:47 AM12/12/16
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I was wondering whether this is the right way of do the analysis?

The syntax looks correct, but the "total" effect doesn't make any sense.  There are 3 IVs, so you need to calculate 3 separate total effects. 

total_s := s + sbb 
total_r := r + rbb
total_c := c + cbb

how I can add my control variables?

The same way you add any other predictor.

and is it possible to have two DVs?

Yes, just include it in the model syntax.

Terrence D. Jorgensen
Postdoctoral Researcher, Methods and Statistics
Research Institute for Child Development and Education, the University of Amsterdam

Mehrnoush Sarafan

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Dec 12, 2016, 2:52:46 PM12/12/16
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Thanks!It’s been really helpful.

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