Bifactor Mediation in SAM

[zhan lin]

Dear All, 

I am currently learning about the Structured After Measurement (SAM) approach and am working on a model that combines a bifactor measurement structure with a mediation model at the structural level, where the bifactor latent variables serve as the mediator. 

I have two related questions:

1) Does SAM support a bifactor measurement model? From the documentation, I understand that first-order and second-order measurement models are supported. I can only find one paper Choi et al. (2025) that uses Global SAM with a bifactor structure. I would appreciate clarification whether bifactor model is supported in SAM and any limitation when using bifactor model in SAM. 

2) If Global SAM is used to fit this model, is bootstrapping available to test the significance of the indirect effects from the mediation model? 

Thank you very much.

Best,

Zhan

[Yves Rosseel]

Hello Zhan,

I recently had a look at this, and bifactors were not working yet, in
the sense that you could obtain point estimates, but standard errors
would rely on the bootstrap.

In the current github version of lavaan (to becomse 0.7-1), they are
supported. For both local and global SAM. But if you still have trouble,
please let me know. I don't have access to 'real' data that involves
bifactor models combined with a structural model.

As for the indirect effect: the bootstrap should work. But I would
recommend using the option se.def = "mc", which will switch to the
Monte-Carlo to compute standard errors (and asymmetric confidence
intervals) for defined (":=") parameters. In the github version only
(for now).

Yves.

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