. 2020 Feb 6;15(2):e0228432. doi: 10.1371/journal.pone.0228432

Table 1. Descriptive statistics for substance variables from 5th through 12th grade.

Experimentation	5^th	6^th	7^th	8^th	9^th	10^th	11^th	12^th
Full Sample
M	.06	.11	.30	.70	1.27	1.75	2.35	2.66
SD	.29	.42	.89	1.46	1.95	2.24	2.48	2.56
% No Use	95.60	91.64	83.68	70.68	55.46	45.50	35.33	30.83
N	639	311	576	590	604	589	600	600
Girls
M	.04	.11	.27	.73	1.31	1.79	2.25	2.56
SD	.21	.44	.81	1.48	1.99	2.29	2.45	2.48
% No Use	97.17	91.45	85.27	69.36	55.74	44.82	36.21	29.84
N	318	152	292	297	305	299	301	305
Boys
M	.08	.11	.34	.67	1.24	1.70	2.44	2.76
SD	.35	.40	.95	1.44	1.92	2.19	2.50	2.62
% No Use	94.08	91.82	82.04	72.01	55.18	46.21	34.45	31.86
N	321	159	284	293	299	290	299	295
Gender d	.14	.00	.08	.04	.04	.04	.08	.08
Frequency of Use	5^th	6^th	7^th	8^th	9^th	10^th	11^th	12^th
Full Sample
M	.04	.07	.15	.40	.66	.94	1.22	1.27
SD	.40	.77	.94	1.50	1.93	2.32	2.95	2.77
% No Use	98.44	97.43	95.30	87.80	81.13	75.00	72.83	68.17
N	639	311	575	590	604	588	600	600
Girls
M	.03	.13	.13	.46	.70	.82	1.02	.92
SD	.34	1.09	.74	1.61	2.05	2.03	2.73	2.37
% No Use	99.06	96.71	95.21	85.19	81.64	76.51	76.08	73.11
N	318	152	292	297	305	298	301	305
Boys
M	.06	.02	.18	.33	.62	1.08	1.41	1.62
SD	.45	.14	1.11	1.38	1.80	2.57	3.14	3.09
% No Use	97.82	98.11	95.41	90.44	80.60	73.45	69.57	63.05
N	321	159	283	293	299	290	299	295
Gender d	.08	.14	.05	.07	.04	.11	.13	.25
Substance Intentions	5^th	6^th	7^th	8^th	9^th	10^th	11^th	12^th
Full Sample
M	.23	.26	.54	1.25	2.03	2.28	2.69	2.67
SD	1.09	.86	1.74	2.66	3.18	3.43	3.70	3.58
% No Intent	91.09	88.75	83.33	69.49	52.98	49.24	42.00	42.00
N	640	311	576	590	604	589	600	600
Girls
M	.19	.16	.56	1.49	2.25	2.31	2.57	2.39
SD	1.07	.66	1.62	2.84	3.36	3.46	3.49	3.29
% No Intent	91.54	92.11	82.88	63.97	50.82	49.16	42.19	42.95
N	319	152	292	297	305	299	301	305
Boys
M	.27	.35	.57	1.00	1.80	2.26	2.81	2.95
SD	1.11	1.01	1.86	2.43	2.96	3.38	3.90	3.83
% No Intent	90.65	85.53	83.80	75.09	55.18	49.31	41.81	41.02
N	321	159	284	293	299	290	299	295
Gender d	.07	.22	.01	.19	.14	.01	.06	.16
Accessibility	5^th	6^th	7^th	8^th	9^th	10^th	11^th	12^th
Full Sample
M	1.58	.69	2.12	3.27	6.28	6.55	8.78	8.84
SD	3.16	1.73	3.94	4.90	5.79	6.19	6.03	6.27
% No Access	63.98	78.32	59.54	51.95	28.19	29.54	16.00	17.33
N	633	309	571	589	603	589	600	600
Girls
M	1.62	.63	2.98	3.87	6.56	6.38	8.66	8.44
SD	3.35	1.73	4.25	5.38	6.13	6.24	6.10	6.52
% No Access	65.51	82.24	60.82	50.84	28.62	34.45	17.61	20.66
N	316	152	291	297	304	299	301	305
Boys
M	1.54	.74	1.94	2.66	5.98	6.72	8.90	9.25
SD	3.00	1.72	3.58	4.27	5.41	6.11	5.95	5.96
% No Access	62.46	74.52	58.21	53.08	27.76	224.48	14.38	13.90
N	317	157	280	292	299	290	299	295
Gender d	.03	.06	.28	.26	.10	.06	.04	.13

M = mean; SD = standard deviation; % No = percentage of youth with scores of 0; N = number of youth reports for a given grade; d = Cohen’s d for mean difference between girls and boys.