IFI scaled

14 views
Skip to first unread message

car...@web.de

unread,
Jul 30, 2018, 5:37:29 AM7/30/18
to lavaan
I have a CFA with the following coefficients: chisq,scaled = 101.791, df = 84, baseline,chisq,scaled = 1525.369. If I simply use the scaled results in the usual formula to calculate the IFI, then I get: (1525.369 - 101.791) / (1525.369 - 84) = 0.988. This also corresponds approximately to the result that EQS produces. Lavaan calculates the following result: ifi,scaled = 0.933. How does this not insignificant difference arise?
Message has been deleted
Message has been deleted
Message has been deleted

car...@web.de

unread,
Jul 30, 2018, 8:13:20 AM7/30/18
to lavaan
After looking at the source code, it's clear. IFI is calculated as follows:
t1 <- X2.null - X2
t2 <- X2.null - df
[...]
IFI scaled is calculated like this:
t1 <- X2.null.scaled - X2.scaled
t2 <- X2.null.scaled
[...]
The denominator therefore does not take df into account. I think that this is not correct. Best regards.

Terrence Jorgensen

unread,
Jul 31, 2018, 6:33:41 AM7/31/18
to lavaan
The denominator therefore does not take df into account. I think that this is not correct.

Thanks for tracking down the problem.  I'll make a note on GitHub to make the change.

Terrence D. Jorgensen
Postdoctoral Researcher, Methods and Statistics
Research Institute for Child Development and Education, the University of Amsterdam

Reply all
Reply to author
Forward
0 new messages