Categorical Variable in SEM PreviousNext
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 Fred Miao posted on Friday, September 14, 2007 - 6:08 am
Hello,

I have a categorical variable "career stage" and I am wondering if I can include it as an independent variable in my model. Career stage is measured with four descriptions (stage 1=exploration; stage 2=establishment; stage 3=maintenance; stage 4=disengagement). While these four measures are descriptive in nature, in theory they are "continuous" in the sense that one goes through stages 1-2-3-4.

Could I then treat career stage like a 4-point Likert scale and put it in my model as an IV ?

Thank you for your advice!

Fred
 Linda K. Muthen posted on Tuesday, September 18, 2007 - 4:29 am
The scale of an independent variable does not matter in model estimation. Independent variables can be binary or continuous. In both cases, they are treated as continuous in model estimation. You can treat the variable as continuous or create a set of dummy variables to represent the categories.
 ehsan malek posted on Monday, April 21, 2008 - 2:05 am
Dear Dr. Muthen,

I am working on a research project which I should use SEM method to confirm my model. I performed the analysis in two different ways:
First I performed an explanatory factor analysis on the results of questionnaires and reduced 74 indicators (which were measured in Likert scale) to 14 factors. Then I used factor scores to develop a SEM model with continuous variables (14 indicators and 6 latent variables). The overall fit of the model was OK according to Chi-square, CFI, and other criteria (P-V=0.25) but 3 of the relations were not significant, while they must be according to the logic and literature in the field of research!
Second, I used 74 indicators as categorical variables and using WLSMV of Mplus software performed the analysis. In this case P-V= 0.0000 but non-significant relations of the first model are now significant.
As I am not familiar enough with this kind of SEM, I will be so happy if you guide me in this case.
Should we check the adequacy of the second model like SEM models with continuous variables?
How about the criteria of model adequacy checking in the SEM with categorical indicators? Can you introduce me an article?
Why usage of SEM with categorical indicators is rare in social sciences? Isn't it strong enough or it is new?

Thank you in advance!
 Linda K. Muthen posted on Monday, April 21, 2008 - 7:57 am
I think your question is how to assess fit when dependent variables in SEM are categorical. You do this the same way as with continuous dependent variables. See the Yu dissertation on our website for further information about this topic.

SEM with categorical variables is no longer rare.
 thanoon younis posted on Tuesday, December 24, 2013 - 5:05 pm
dear dr. Muthen
i want to apply 6 types of models on SEM so i need your help to write these commands in mplus.
1- independent continuous variables.
2- independent ordered categorical variables.
3- independent dichotomous variables.
regards
 Linda K. Muthen posted on Wednesday, December 25, 2013 - 9:59 am
All independent variables are treated as continuous variables in regression. For an ordinal variable, you can leave it ordinal or create a set of dummy variables.
 thanoon younis posted on Wednesday, December 25, 2013 - 4:55 pm
Dear dr. Linda
I am sorry I mean observed variables not not independent because when I used mplus I saw this term "weight variable" and "grouping variable"for one variable only and I can select categorical variable to all variables not only one like grouping and weight variables then how can I analyze more than one variables and how can I select continues variables. Grouping var. Means dichotomous? And categorical var. Means ordered? Then what about continues how can I chose it.
Regards
 Linda K. Muthen posted on Thursday, December 26, 2013 - 8:59 am
All variables are assumed to be continuous unless they are designated as categorical, count. etc. See pages 541-549 of the user's guide.
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