Table 1a:

Weighted Percentage of Tobacco and Product-Specific Initiation at W2 or W3 Among W1 Never Users.

W1 (2013/14)	W2 (2014/15) or W3 (2015/16)
	P12M Initiation		P30D Initiation		Frequent P30D Initiation
Youth	Weighted %	95%CI	Weighted %	95%CI	Weighted %	95%CI
Never tobacco use	24.4	(23.4–25.4)	9.5	(8.8–10.2)	1.3	(1.1–1.6)
Never cigarette use	9.9a,d	(9.3–10.6)	4.7a,b,d	(4.2–5.3)	0.6b,c	(0.5–0.8)
Never ENDS use	22.7a,e,f,g	(21.6–23.7)	6.4a,e,f,g	(5.8–7.1)	0.9e,f,g	(0.7–1.2)
Never hookah use	8.9e,i	(8.3–9.7)	3.4b,e,i	(3.0–3.8)	0.2b,e,i	(0.1–0.4)
Never cigar use	9.0f,j	(8.3–9.7)	4.0f,j	(3.7–4.4)	0.1c,f,j	(0.1–0.2)
Never smokeless use	4.2d,g,i,j	(3.7–4.7)	1.8d,g,i,j	(1.6–2.1)	0.5g,i,j	(0.4–0.7)
Young adults	Weighted %	95%CI	Weighted %	95%CI	Weighted %	95%CI
Never tobacco use	22.8	(20.0–26.0)	12.2	(10.1–14.6)	1.7	(1.1–2.7)
Never cigarette use	10.3a,b,d	(8.8–12.0)	6.1d	(5.1–7.4)	1.1b,c	(0.7–1.6)
Never ENDS use	28.4a,e,f,g	(26.5–30.4)	7.4g	(6.4–8.4)	1.0e,f,g	(0.7–1.5)
Never hookah use	14.1b,e,i	(12.5–15.8)	6.4i	(5.3–7.7)	0.2†b,e	(0.1–0.4)
Never cigar use	12.0f,j	(10.8–13.4)	7.2j	(6.2–8.4)	0.3†c,f	(0.2–0.6)
Never smokeless use	2.5d,g,i,j	(2.1–2.9)	1.4d,g,i,j	(1.1–1.7)	0.4g	(0.2–0.6)
Adults 25+	Weighted %	95%CI	Weighted %	95%CI	Weighted %	95%CI
Never tobacco use	4.0	(3.1–5.0)	2.7	(2.0–3.6)	0.4†	(0.2–0.9)
Never cigarette use	2.4a,d	(1.8–3.2)	1.8b,d	(1.3–2.6)	0.4†	(0.2–0.7)
Never ENDS use	6.7a,e,f,g	(6.3–7.2)	2.3e,g	(2.0–2.5)	0.5e,g	(0.4–0.6)
Never hookah use	1.4e,h,i	(1.2–1.7)	0.7b,e,h	(0.6–0.9)	0.0e,h	(0.0–0.1)
Never cigar use	3.3f,h,j	(2.8–3.9)	2.1h,j	(1.8–2.6)	0.3h,j	(0.2–0.5)
Never smokeless use	0.7d,g,i,j	(0.5–0.8)	0.5d,g,j	(0.4–0.7)	0.1†g,j	(0.0–0.1)

Notes:

Abbreviations: W2 = Wave 2; W3 = Wave 3; W1 = Wave 1; P12M = past 12-month; P30D = past 30-day; CI= confidence intervals; ENDS* = electronic nicotine delivery system

W1 total group unweighted denominators (P12M initiation/P30D initiation/Frequent P30D initiation):

Never tobacco use – youth (ages 12–17): 8,245/8,143/8,078; young adults (ages 18–24): 1,312/1,308/1,295; adults 25+ (ages 25 and older): 2,043/2,046/2,039

Never cigarette use - youth: 9,596/9,590/9,576; young adults: 2,310/2,310/2,294; adults 25+: 2,903/2,906/2,894

Never ENDS use - youth: 9,849/9,793/9,764; young adults: 3,697/3,651/3,639; adults 25+: 11,532/11,403/11,431

Never hookah use - youth: 10,239/10,231/10,199; young adults: 2,921/2,924/2,920; adults 25+: 13,071/13,083/13,065

Never cigar use - youth: 9,916/9,876/9,849; young adults: 2,817/2,818/2,770; adults 25+: 7,494/7,510/7,444

Never smokeless use - youth: 10,252/10,248/10,236; young adults: 5,145/5,152/5,135; adults 25+: 13,116/13,155/13,094

Analysis included youth, young adult, and adult 25+ W1never tobacco or tobacco product users with data at W1, W2, and W3. Respondent age was calculated based on age at W1. W3 longitudinal (all-waves) weights were used to calculate estimates.

Never tobacco/product initiation is defined as not having used any tobacco or the specific product, even once or twice in lifetime.

1) P12M initiation: Defined as a never user at W1 who used any tobacco or the specific product within the past 12 months at W2 or W3.

2) P30D initiation (a subset of P12M initiation): Defined as a never user at W1 who used any tobacco or the specific product within the past 30 days at W2 or W3.

3) Frequent P30D initiation (a subset of P30D initiation): Defined as a never user at W1 who used any tobacco or the specific product within the past 30 days on at least 20 or more days at W2 or W3.

All significance testswere done between product initiations only (not any tobacco initiation).

^adenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between cigarette and ENDS

^bdenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between cigarette and hookah

^cdenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between cigarette and cigar

^ddenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between cigarette and smokeless

^edenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between ENDS and hookah

^fdenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between ENDS and cigar

^gdenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between ENDS and smokeless

^hdenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between hookah and cigar

ⁱdenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between hookah and smokeless

^jdenotes significant difference at p<0.005 (Bonferroni corrected for ten comparisons) between cigar and smokeless

^*Respondents were asked about “e-cigarettes” at W1 and “e-products” (i.e., e-cigarettes, e-cigars, e-pipes, and e-hookah) at W2 and W3

The logit-transformation method was used to calculate the 95% CIs.

^†Estimate should be interpreted with caution because it has low statistical precision. It is based on a denominator sample size of less than 50, or the coefficient of variation of the estimate or its complement is larger than 30%.

Analyses were run on the W1, W2, and W3 Public Use Files (https://doi.org/10.3886/ICPSR36498.v8).