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608
Appendix C
MECVI
Except for a scale factor, MECVI is identical to BCC.
where if the
Emulisrel6 command has been used, or if it
has not.
See also “BCC” on p. 606.
Note: Use the \mecvi text macro to display the modified ECVI statistic in the output
path diagram.
Comparisons to a Baseline Model
Several fit measures encourage you to reflect on the fact that, no matter how badly your
model fits, things could always be worse.
Bentler and Bonett (1980) and Tucker and Lewis (1973) suggested fitting the
independence model or some other very badly fitting baseline model as an exercise to
see how large the discrepancy function becomes. The object of the exercise is to put
the fit of your own model(s) into some perspective. If none of your models fit very
well, it may cheer you up to see a really bad model. For example, as the following
output shows, Model A from Example 6 has a rather large discrepancy ( )
in relation to its degrees of freedom. On the other hand, 71.544 does not look so bad
compared to 2131.790 (the discrepancy for the independence model).
()
()
() ()
()
() ()
() ()
()
∑
∑
=
=
+
−−
+
+==
G
g
gg
G
g
gg
gg
g
pp
pN
pp
a
qF
n
1
1
3
2
3
2
ˆ
1
BCCMECVI
a
g()
N
g()
1–
NG–
------------------=
a
g()
N
g()
N
---------=
C
ˆ
71.544=