Other Indices of Fit - Bentler-Bonett Normed Fit Index

One of the most historically important and original fit indices, the Bentler-Bonett index measures the relative decrease in the discrepancy function caused by switching from a "Null Model" or baseline model, to a more complex model. It is defined as:

, where (125)

 = the discrepancy function for the "Null Model"

 = the discrepancy function for the k'th model

This index approaches 1 in value as fit becomes perfect. However, it does not compensate for model parsimony.