Using the Modification Index and Standardized Expected Parameter Change for Model Modification

Abstract

Model modification is oftentimes conducted after discovering a badly fitting structural equation model. During the modification process, the modification index (MI) and the standardized expected parameter change (SEPC) are 2 statistics that may be used to aid in the selection of parameters to add to a model to improve the fit. The purpose of this study was to extend the literature by examining the performance of the MI and the SEPC used independently and in conjunction with one another in terms of arriving at the correct confirmatory factor model. The results indicated that, in general, the SEPC outperformed the MI when arriving at the correct confirmatory factor model. However, they performed more similarly as factor loading size, sample size, and misspecified parameter size increased. The author provides recommendations on when the MI and SEPC perform more optimally.

Keywords:

• model misspecification
• model modification
• modification index
• specification searches
• standardized expected parameter change