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Example 11
Fitting Models A and B in a Single Analysis
It is possible to fit both Model A and Model B in the same analysis. The file
Ex11-ab.amw in the Amos Examples directory shows how to do this.
Model C for Girls and Boys
You might consider adding additional constraints to Model B, such as requiring every
parameter to have the same value for boys as for girls. This would imply that the entire
variance/covariance matrix of the observed variables is the same for boys as for girls,
while also requiring that the Felson and Bohrnstedt model be correct for both groups.
Instead of following this course, we will now abandon the Felson and Bohrnstedt
model and concentrate on the hypothesis that the observed variables have the same
variance/covariance matrix for girls and boys. We will construct a model (Model C)
that embodies this hypothesis.
E Start with the path diagram for Model A or Model B and delete (Edit > Erase) every
object in the path diagram except the six observed variables. The path diagram will
then look something like this:
Each pair of rectangles needs to be connected by a double-headed arrow, for a total of
15 double-headed arrows.