# Compare specific coefficients across two models

19 views

### Matti Cervin

Jul 15, 2019, 10:37:40 AM7/15/19
to lavaan
I am working on a study in which we want to compare a specific coefficient in Model1 to a specific coefficient in Model2. I know that I can compare overall model fit using lavaan, but can I also compare specific coefficients between models?

Example:

Model1<-'
f1=~v1+v2+v3
f2=~v4+v5+v6
f3=~v7+v8+v9

f1~~f2
f1~~f3
f2~~f3'

Model2
<-'
f1=~v1+v2+v3
f2=~v10+v11+v12
f3=~v7+v8+v9

f1~~f2
f1~~f3
f2~~f3'

Now I want to examine whether there is a statistically significant difference between the f1~~f2 coefficient in Model1 as compared to the f1~~f2 coefficient in Model2. Is this possible? If so, how?

### Terrence Jorgensen

Jul 17, 2019, 11:51:30 PM7/17/19
to lavaan
Now I want to examine whether there is a statistically significant difference between the f1~~f2 coefficient in Model1 as compared to the f1~~f2 coefficient in Model2. Is this possible? If so, how?

Comparing coefficients from different models would not be feasible unless the parameter estimates were truly independent (in which case the SE of their difference would be the square-root of the sum of the 2 squared SEs), but that does not sound feasible if all 6 indicators (parallel items?) really measure the same factor "f2".

Does using a single model with separate factors make sense?

`model <- 'f1 =~ v1+v2+v3f21 =~ v4+v5+v6f22 =~ v10+v11+v12f3 =~ v7+v8+v9f1 ~~ a*f21 + b*f22 + f3f21 ~~ f22 + f3f22 ~~ f3'fit <- cfa(model, data)lavTestWald(fit, constraints = "a == b")`

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

### Matti Cervin

Jul 18, 2019, 4:45:32 AM7/18/19
Yes, that actually makes a lot of sense. I will try it immediately. Thanks a lot!

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