During the confirmatory factor analyses, selected model-fit indices were also used to measure the extent to which a model with an assumed a-priori structure “fitted the data.” For the ICCS analysis, model fit was assessed primarily through use of the root-mean square error of approximation (RMSEA), the comparative fit index (CFI), and the non-normed fit index (NNFI), all of which are less affected than other indices by sample size and model complexity (see Bollen & Long, 1993).
It was assumed, with respect to the analysis, that RMSEA values over 0.10 would suggest an unacceptable model fit while values below 0.05 would indicate a close model fit. As additional fit indices, CFI and NNFI are bound between 0 and 1. Values below 0.90 and 0.95 indicate a non-satisfactory model fit whereas values greater than 0.95 suggest a close model fit.
Schulz, Ainley, & Fraillon, 2011, p161
References
Schulz, W., Ainley, J., & Fraillon, J. (2011). ICCS 2009 technical report. Amsterdam, The Netherlands: International Association for the Evaluation of Educational Achievement (IEA).
