Table 4.

Regression model of age of first use of alcohol, cannabis and tobacco on average daily minutes of screen time (square root transformed).

Predictor	Levels	Beta estimate	SE	DF	t Value	p = Pr > |t|
Intercept		20.40	0.19	105	106.69	<0.0001
Data collection year	2012 (reference)
	2013	−0.23	0.13	35,000	−1.79	0.07
	2014	−0.13	0.13	35,000	−0.99	0.32
	2015	0.01	0.13	35,000	0.06	0.95
	2016	0.01	0.14	35,000	0.10	0.92
Sex	Female (reference)
	Male	−0.15	0.08	35,000	−2.05	0.04
Ethnicity	White (reference)
	Black	3.08	0.18	35,000	16.71	<0.0001
	Asian	0.97	0.16	35,000	6.20	<0.0001
	Off-reserve aboriginal	1.66	0.23	35,000	7.21	<0.0001
	Latin American/Hispanic	1.97	0.24	35,000	8.19	<0.0001
	Other/mixed	1.44	0.19	35,000	7.76	<0.0001
Spending money	Zero (reference)
	$1 to $20	−0.18	0.14	35,000	−1.27	0.20
	$21 to $100	−0.46	0.13	35,000	−3.53	0.00
	More than $100	−0.69	0.13	35,000	−5.28	<0.0001
	Don't know	−0.03	0.16	35,000	−0.17	0.86
Current drinker	Non-drinker (reference)
	Current drinker	0.26	0.10	35,000	2.66	0.01
Current cannabis user	Non-user (reference)
	Current user	0.84	0.12	35,000	7.05	<0.0001
Current smoker	Non-smoker (reference)
	Current smoker	0.81	0.13	35,000	6.16	<0.0001
Age of first use - alcohol	8	0.97	0.23	35,000	4.28	<0.0001
	9	0.65	0.44	35,000	1.49	0.14
	10	0.17	0.30	35,000	0.58	0.56
	11	0.57	0.34	35,000	1.64	0.10
	12	−0.53	0.21	35,000	−2.51	0.01
	13	−0.22	0.18	35,000	−1.23	0.22
	14	−0.52	0.15	35,000	−3.59	0.00
	15	−0.41	0.14	35,000	−3.03	0.00
	16	−0.17	0.13	35,000	−1.27	0.20
	17	0.13	0.18	35,000	0.71	0.48
	18	1.76	0.39	35,000	4.50	<0.0001
	Never used (reference)
Age of first use - cannabis	8	4.76	0.39	35,000	12.08	<0.0001
	9	2.97	0.77	35,000	3.87	0.00
	10	1.67	0.58	35,000	2.88	0.00
	11	1.42	0.55	35,000	2.59	0.01
	12	1.14	0.34	35,000	3.39	0.00
	13	0.80	0.24	35,000	3.32	0.00
	14	0.75	0.18	35,000	4.21	<0.0001
	15	0.60	0.15	35,000	3.86	0.00
	16	0.71	0.14	35,000	5.11	<0.0001
	17	0.75	0.17	35,000	4.52	<0.0001
	18	1.00	0.42	35,000	2.41	0.02
	Never used (reference)
Age of first use - cigarettes	8	3.88	0.32	35,000	11.95	<0.0001
	9	1.78	0.57	35,000	3.10	0.00
	10	1.63	0.47	35,000	3.43	0.00
	11	1.99	0.47	35,000	4.19	<0.0001
	12	1.01	0.30	35,000	3.40	0.00
	13	1.09	0.25	35,000	4.41	<0.0001
	14	0.92	0.19	35,000	4.90	<0.0001
	15	0.65	0.17	35,000	3.81	0.00
	16	0.66	0.15	35,000	4.46	<0.0001
	17	0.55	0.17	35,000	3.20	0.00
	18	0.58	0.43	35,000	1.35	0.18
	Never used (reference)