Table 2.

Conditional likelihood ratio test of overall model fit and Global DIF

	Model	Homogeneity	Differential Item Functioning by sex	Differential Item Functioning by education
PSS-14	RM	χ2(55) = 3828.3, p < 0.001	χ2(55) = 575.1, p < 0.001	χ2(55) = 320.9, p < 0.001
Perceived Stress	RM	χ2(27) = 1409.7, p < 0.001	χ2(27) = 177.8, p < 0.001	χ2(27) = 82.2, p < 0.001
	GLLRM	χ2(96) = 94.4, p = 0.440	χ2(80) = 111.8, p = 0.012	χ2(88) = 104.1, p = 0.080
Perceived Control	RM	χ2(27) = 713.4, p < 0.001	χ2(27) = 197.2, p < 0.001	χ2(27) = 104.1, p < 0.001
	GLLRM	χ2(55) = 62.5, p = 0.224	χ2(39) = 39.0, p = 0.469	χ2(47) = 70.9, p = 0.014

The subgroups were defined according to lower and higher scores (i.e. homogeneity) to evaluate overall model fit; and according to sex (men; women) and education (Up to high school; Technical education or University) to evaluate Global Differential Item Functioning