Measuring motivation for medical treatment: confirming the factor structure of the Achievement Motivation Index for Medical Treatment (AMI-MeT)

Table 2 Test of measurement equivalences for Achievement Motive Index for Medical Treatment

Fit indexes	χ2	df	p	χ²/df	Δχ²	Δdf	p’	CFI	GFI	AGFI	AIC	RMSEA
Configural invariance model	244.051	102	.000	2.393	-	-	-	.911	.929	.886	370.051	.048
Weak invariance model	265.043	118	.000	2.246	20.992	16	.179	.908	.923	.893	359.043	.045
Strong invariance model	301.086	120	.000	2.509	57.035	18	.000	.887	.912	.878	391.086	.049
Complete invariance model	400.484	140	.000	2.861	156.433	38	.000	.837	.888	.868	450.484	.055

Equivalences for AMI-Met were tested in sequence by placing constraints on the parameters (i.e., factor loadings, factor variances/covariance, and error variances). Configural invariance is the simplest form without any constraints on the parameters. Weak invariance constrains the factor loadings; strong invariance constrains the factor loadings and factor variances/covariance; and complete invariance constrains the factor loadings, factor variances/covariance, and error. The difference in the χ² values (Δχ²) and the degrees of freedom (Δdf) were calculated as follows: Δχ ² = χ ² _{nested model} − χ ² _{configural invariance model}, and Δdf = df_{nested model} − df_{configural invariance model}. p’ indicates the significance distributed from Δχ² and Δdf [24]

ISSN: 1472-6947