Bias due to conditioning on a collider PreviousNext
Mplus Discussion > Structural Equation Modeling >
Message/Author
 nata posted on Monday, March 10, 2014 - 7:22 am
Dear Mplus-Team,

I am running a full SEM Which I have 9 observed binary indicators (x1-x11), 3 latent factor (f1-f3), 1 mediating variable (m), 3 confounders (x12-x14) and 1 binary outcome (y) . The model is the Following:

BY f1 x1-x4;
f2-BY x5 x8;
f3-BY x9 x11;

y ON m f1 f2 f3 x12 x13 x14;

ON m f1 f2 f3 x12 x13 x14;

f1 ON x12 x13 x14;
ON f1 f2 f3 x12 x13 x14;
ON f1 f3 x12 x13 x14;

Now, if the model is correct from a syntactic point of view, the variable m should be a collider. I was wondering if the estimates of the direct and indirect effects on y that provides Mplus are biased or not?

Thanks
 Bengt O. Muthen posted on Monday, March 10, 2014 - 4:49 pm
You have 3 statements starting with ON which does not translate to Mplus language.

If the model is correctly specified, there is no bias.
 nata posted on Wednesday, March 12, 2014 - 8:53 am
Sorry, probably there was a problem in the copy&past process. Here is the exact formulation of the model:

f1 BY x1-x4;
f2 BY x5-x8;
f3 BY x9-x11;

y ON m f1 f2 f3 x12 x13 x14;
m ON f1 f2 f3 x12 x13 x14;
f1 ON x12 x13 x14;
f2 ON f1 f3 x12 x13 x14;
f3 ON f1 x12 x13 x14;

Thanks
 Bengt O. Muthen posted on Wednesday, March 12, 2014 - 4:27 pm
This model specification looks fine. Under the usual causal inference assumptions, the Mplus Model Indirect estimates of direct and indirect effects are consistent.
Back to top
Add Your Message Here
Post:
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Password:
Options: Enable HTML code in message
Automatically activate URLs in message
Action: