Restricting residual variances to be ... PreviousNext
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 Vika Savalei posted on Tuesday, April 18, 2006 - 11:14 am
I am trying to run a 1-factor model with one of the residual variances constrained to remain positive.

I've consulted example 5.20 in the new manual, and based on it set up the following:

VARIABLE: NAMES ARE y1-y5;
MODEL: f1 BY y1-y5 (V1-V5);
MODEL CONSTRAINT:
V5 > 0;

This runs, but the output is the same as if the last two lines were never there. What am I doing wrong?

Thanks much!
 Linda K. Muthen posted on Tuesday, April 18, 2006 - 11:57 am
v5 refers to a factor loading not a residual variance. To refer to a residual variance, say:

y1-y5 (v1-v5);

and remove the labels from the factor loadings. If you continue to have problems, send the input, data, output, and your license number to support@statmodel.com.
 Vika Savalei posted on Tuesday, April 18, 2006 - 10:03 pm
Hi Linda,

Thanks for your message. I'm not sure I understand how to modify the syntax. I already say: f1 on y1-y5 (v1-v5), except I use capital V's. Should I repeat this statement again with lower case v's as you suggest? Also, what does it mean, "remove labels from factor loadings"?
 Linda K. Muthen posted on Wednesday, April 19, 2006 - 6:35 am
You refer to residual variances by the name of the variable alone. ON is for regression coefficients. BY is for factor loadings. Try

VARIABLE: NAMES ARE y1-y5;
MODEL: f1 BY y1-y5;
y1-y5 (V1-V5);
MODEL CONSTRAINT:
V5 > 0;
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