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 Anonymous posted on Wednesday, October 20, 2004 - 9:57 am
I am interested in running a vanishing tetrad test to determine if the items on a scale are effect or causal indicators. To run this test, I need to obtain the implied covariance matrix for a model with causal indicators. However, I am unsure of how to do this in MPlus. I would definitely appreciate any guidance. Thank you!
 Linda K. Muthen posted on Wednesday, October 20, 2004 - 10:07 am
The RESIDUAL option of the OUTPUT command is used to request model estimated means, variances, and covariances.
 Anonymous posted on Wednesday, October 20, 2004 - 10:09 am
Thanks for getting back to me so quickly! I'm actually wonder how to set up the model. I have no problem specifying an effect indicators model where the paths go from the latent variable to the individual items. (It's just a CFA model.) However, I'm not clear on how to switch the direction so that the paths go from the individual items to the latent variable.
 Linda K. Muthen posted on Wednesday, October 20, 2004 - 10:37 am
I copied this from a former post by Bengt.

"In some applications it may be more natural to let a factor be defined as being influenced by indicators, rather than influencing the indicators. An example is SES. Mplus handles this modeling by the following model statements.

f by y*;
f@0;
f on x1@1 x2 x3;

Note that f by y* (that is, freeing the factor loading for the single indicator y) is the same as y on f. f has to be defined by some y - if instead you use the dummy definition

f by y@0;
y on f;

the estimate shows up in f by y."
 Anonymous posted on Wednesday, October 20, 2004 - 10:40 am
Wondeful! Thanks so much!
 ds posted on Monday, November 21, 2005 - 8:10 am
I am trying to run a cfa with 3 latent variables and a categorical outcome variable.

As part of this model, I have one "latent" variable with 2 categorical indicators (hs grad, minority) and 1 continuous indicator (age). I want to use these 3 indicators as effect indicators of background risk.

However, I am not clear how to accomplish this using Mplus (again, switching the arrows). Any help would be appreciated!
 Linda K. Muthen posted on Monday, November 21, 2005 - 8:28 am
f BY y*; ! defining the factor; same as
! regressing y on f
f@0;

f ON age@1 hsgrad minority;
 ds posted on Saturday, November 26, 2005 - 11:01 am
Thank you!
In terms of the first line

f BY y*;

For the CFA, should I also be including all latent variables included where the above says "y*"?

DS
 Linda K. Muthen posted on Monday, November 28, 2005 - 5:10 pm
f BY is used only to define F as a factor name. The factor itself is specified using the f ON statment.
 Al Farrell posted on Tuesday, January 03, 2006 - 1:59 pm
I'm trying to run a causal indicator model using the f by Y* syntax, but keep getting an error message:

*** ERROR in Model command
Unknown variable: Y

Does Y have to be an actual variable in the data set?

Thank you!
 Linda K. Muthen posted on Tuesday, January 03, 2006 - 3:36 pm
Yes, the variables have to be in the data set and part of the NAMES or USEVARIABLES options.
 BOUHARAOUI FATIMA posted on Friday, October 13, 2006 - 12:31 pm
I want to do a MIMIC MODEL (30 items as causal indicators, and 2 items as effect indicators) , but in the end, I want to calculate the latent score variable, how can I obtain this?

thanks
 Linda K. Muthen posted on Friday, October 13, 2006 - 2:52 pm
You can obtain factor scores by using the FSCORES option of the SAVEDATA command. Example 5.8 shows a MIMIC model.
 liesbethvanosch posted on Friday, March 30, 2007 - 9:42 am
I am trying to run the following causal indicator model with four continuous indicators (api_kop, api_tijd, api_mee and api_and) for the latent variable action_i, and with smerenbn as the only dependent variable related to action_i.

action_i BY smerenbn@0;
smerenbn ON action_i;
action_i@0;
action_i ON api_kop@1 api_tijd api_mee api_and;

Is this correct?

Although this model above runs without problems, I run into trouble when adding any other paths with smerenbn as dependent variable (which is necessary for my model). I keep getting error messages: THE DEGREES OF FREEDOM FOR THIS MODEL ARE NEGATIVE. THE MODEL IS NOT IDENTIFIED. NO CHI-SQUARE TEST IS AVAILABLE. CHECK YOUR MODEL.

Is it not possible to use the y variable (smerenbn) in any other instance than to define the factor?
 Linda K. Muthen posted on Friday, March 30, 2007 - 9:56 am
You do not need to put a latent variable behind an observed variable in Mplus. Just say:

smerenbn ON api_kop@1 api_tijd api_mee api_and;

If you want to put a latent variable behind an observed variable, the correct format is:

action_i BY smerenbn@1;
smerenbn@0;
 Bengt O. Muthen posted on Friday, March 30, 2007 - 10:03 am
Looks like you are doing formative indicator analysis which is fine as you have specified it, although all you have to say is

action_i BY;

to define the action_i factor (nothing needs to follow BY).

There is no problem in letting your y (smerenbn) be a dependent variable for other predictors as well. If you can't see the problem, send your input, output, data, and license number to support@statmodel.com.
 matthew urato posted on Tuesday, August 11, 2009 - 11:59 am
I have a latent variable model with one latent variable being determined by 3 causal (or formative) indicators. There are no effect indicators in this model. I also have this latent variable determining 3 endogenous variables. For the purpose of scaling, can I set any of these 6 paths to 1? Also, in addition to this, do I have to constrain the error variance of this latent variable in any way?
 Linda K. Muthen posted on Wednesday, August 12, 2009 - 8:51 am
Yes, you can fix any path to one. The error variance must be fixed at zero.
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