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Why
didn't Amos report GFI, PGFI, AGFI and RMR?
Amos does not report GFI, PGFI, AGFI and RMR when you
estimate means and intercepts. This is because it is not
clear how to incorporate means and intercepts into the
conventional formulas for these statistics. One
possibility is to calculate these statistics based on
the observed variances/covariances and the fitted
(implied) variances/covariances, leaving the means and
intercepts out of the fit measure. That way of computing
the statistics could be useful and is certainly
defensible. It would make a great deal of sense in those
models where means and intercepts are estimated but not
constrained. On the other hand, for models that
constrain means and intercepts it is important to pay
attention to how well the model reproduces the means and
intercepts, as well as the variances/covariances.
Another approach would be to generalize the definitions
of those statistics to somehow incorporate failure to
fit means and intercepts. So far, a unique, obviously
correct, way of doing this has not been proposed.
For these reasons, the design decision was made not to
report GFI, PGFI, AGFI and RMR when means and intercepts
are estimated.
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