Table 4.

Influence of demographic, sleep-related and school attendance variables on school grades by academic subject.

Explanatory variables	Geography			History			English			Dutch
	b	t-value	p-value	b	t-value	p-value	b	t-value	p-value	b	t-value	p-value
sex	0.125	2.125	0.0342	0.132	1.651	0.0995	−0.274	−2.857	0.0045	−0.326	−6.446	<0.0001
chronotype	−0.071	−2.559	0.0108	−0.049	−1.316	0.1889	0.014	0.315	0.7528	−0.034	−1.414	0.1581
late arrivals	−0.052	−2.489	0.0132	−0.088	−3.299	0.0011	−0.070	−2.066	0.0395	−0.048	−2.685	0.0075
class dismissals	−0.076	−3.575	0.0004	−0.047	−1.656	0.0985	−0.067	−1.953	0.0515	−0.101	−5.545	<0.0001
sick leaves (days)	−0.014	−2.723	0.0067	−0.022	−3.097	0.0021	−0.012	−1.408	0.1598	−0.014	−3.175	0.0016
	biology			physics			chemistry			mathematics
explanatory variables	b	t-value	p-value	b	t-value	p-value	b	t-value	p-value	b	t-value	p-value
sex	−0.116	−1.349	0.1787	0.082	0.512	0.6099	0.249	2.164	0.0319	−0.188	−1.823	0.0690
chronotype	−0.145	−3.423	0.0007	−0.058	−0.738	0.4621	−0.141	−2.412	0.0170	−0.124	−2.543	0.0114
late arrivals	−0.062	−1.939	0.0536	0.020	0.510	0.6114	−0.093	−2.074	0.0397	−0.065	−1.846	0.0656
class dismissals	−0.079	−2.152	0.0323	−0.256	−3.313	0.0013	−0.101	−3.018	0.0030	−0.126	−3.435	0.0007
sick leaves (days)	−0.031	−3.910	0.0001	−0.018	−1.525	0.1303	−0.034	−9.296	0.0012	−0.031	−3.290	0.0011

The model estimates (b coefficients), the test statistic (t-test), and the p-values associated with each independent variable are reported.