Table 3. Model fit indices and external validity for the ant colony optimised short version compared to 100,000 random combinations of items.

Model	Factors	parb	χ2c	CFId	RMSEAe	SRMRf	Adj. R2g
ACO short versiona	101	169	252.3*	0.980*	0.046*	0.038*	0.425*
100,000 random combinationsa	101	169	716.7	0.918	0.080	0.067	0.389
				(0.02)	(0.01)	(0.01)	(0.02)

^amodelling corresponds to the factorial assumptions of model 7b.

^bpar: Number of estimated parameters.

^cchi-square statistic

^dCFI: Comparative Fit Index.

^eRMSEA: Root Mean Squared Error of Approximation.

^fSRMR: Standard Root Mean Residual.

^gAdj. R² = external validity (variance explained).

*Best fit indices are highlighted with asterisks.