Table 2.

Results of hierarchical multiple regression analyses in which age, gender, study addiction Wave 1, the five-factor model dimensions (neuroticism, extroversion, openness, agreeableness, and conscientiousness), and learning time during and outside university classes were entered as independent variables for study addiction Wave 2

		Study addiction Wave 2 (Norway)a		Study addiction Wave 2 (Poland)b
Step	Predictor	β	ΔR2	β	ΔR2
1	Genderc	−.088**	.325**	−.018	.442**
	Age	.014	—	.055*	—
	Study addiction Wave 1	.546**	—	.661**	—
2	Genderc	−.072**	.008*	−.016	.004
	Age	.018	—	.048	—
	Study addiction Wave 1	.522**	—	.649**	—
	Extroversion	.026	—	−.041	—
	Agreeableness	−.040	—	−.015	—
	Conscientiousness	.023	—	.046	—
	Neuroticism	.082**	—	.017	—
	Openness	.000	—	.035	—
3	Genderc	−.070**	.002	−.014	.011**
	Age	.013	—	.047	—
	Study addiction Wave 1	.507**	—	.601**	—
	Extroversion	.033	—	−.034	—
	Agreeableness	−.035	—	−.014	—
	Conscientiousness	.014	—	.033	—
	Neuroticism	.087**	—	.027	—
	Openness	−.003	—	.037	—
	Study time during classes Wave 1	.020	—	.035	—
	Study time outside classes Wave 1	.050	—	.102**	—
	Total R2		.336*	—	.458**

^aNorwegian sample. ^bPolish sample. ^c0 = women, 1 = men.

*p < .05. **p < .01.