Table 2

Estimated marginal means, SEs, univariate F statistics and % of ‘don’t know’ of each message condition

 Session1 outcomes/conditions VLNC message, N=468 E-cigarette message, n=484 Combined message, n=476 Control, n=473 Univariate F statistics Adjusted P value Perceived absolute harm of VLNCs* (1–5 scale) EMM (95% CI) 4.09 (3.99 to 4.19)a 3.81 (3.71 to 3.90)b 4.03 (3.93 to 4.13)ac 3.87 (3.78 to 3.97)bc F(3, 1687)=7.33, p<0.001, ηp2=0.013 0.008 % of ‘don’t know’ 10.3 11.4 11.4 9.5 Perceived absolute addictiveness of VLNCs (1–5 scale) EMM (95% CI) 3.68 (3.58 to 3.78) 3.74 (3.64 to 3.84) 3.65 (3.55 to 3.75) 3.71 (3.61 to 3.82) F(3, 1633)=0.64, p=0.59, ηp2=0.001 0.70 % of ‘don’t know’ 12.9 14.0 13.7 13.4 Interest in trying VLNC* (1–7 scale) EMM (95% CI) 3.09 (2.89 to 3.28) 2.95 (2.76 to 3.14) 3.08 (2.90 to 3.27) 3.15 (2.95 to 3.34) F(3, 1755)=0.77, p=0.51, ηp2=0.001 0.70 % of ‘don’t know’ 7.1 8.5 5.0 6.4 Intention to switch completely to e-cigarettes† (1–7 scale) EMM (95% CI) 3.15 (2.96 to 3.33) 2.97 (2.79 to 3.15) 2.91 (2.73 to 3.09) 2.86 (2.68 to 3.05) F(3, 1324)=2.08, p=0.10, ηp2=0.005 0.40 % of ‘don’t know’ 9.5 5.6 7.5 6.5 Perceived risk of nicotine (1–7 scale) EMM (95% CI) 4.81 (4.64 to 4.99) 4.87 (4.69 to 5.04) 4.75 (4.58 to 4.93) 4.94 (4.76 to 5.11) F(3, 1807)=0.75, p=0.52, ηp2=0.001 0.70 % of ‘don’t know’ 5.6 4.1 4.1 2.5 Intention to quit smoking*† (1–7 scale) EMM (95% CI) 3.94 (0.08) 3.69 (0.08) 3.86 (0.08) 3.87 (0.08) F(3, 1390)=1.52, p=0.21, ηp2=0.003 0.56 % of ‘don’t know’ ‘How interested are you in quitting smoking in the next 6 months?’ 4.2 6.1 4.2 2.3 ‘How much do you plan to quit smoking in the next 6 months?’ 7.8 6.3 5.0 6.2 ‘How likely are you to quit smoking in the next 6 months?’ 9.4 8.0 6.9 6.2
 Session 2 Outcome/conditions VLNC message, N=379 E-cigarette message, n=383 Combined message, n=374 Control, n=374 Univariate F statistics Perceived absolute harm of VLNCs at Session 2 (1–5 scale) EMM (95% CI) 3.68 (3.57 to 3.80) 3.62 (3.51 to 3.74) 3.68 (3.56 to 3.79) 3.62 (3.50 to 3.73) F(3, 1198)=0.36, p=0.78, ηp2=0.001 0.78 % of ‘don’t know’ 20.8 20.4 20.1 21.1 Number of cigarettes smoked per day in the past 2 weeks at Session 2* EMM (95% CI) 12.40 (11.88 to 12.91) 11.98 (11.46 to 12.50) 12.27 (11.75 to 12.79) 12.00 (11.47 to 12.52) F(3, 1132)=0.61, p=0.61, ηp2=0.002 0.70
• Results from analyses of covariance (ANCOVAs).

• Bold indicates significance at adjusted p<0.05.

• P values were adjusted using the False Discovery Rate method.29

• Estimates with different superscripts in each row were significantly different at adjusted p<0.05.

• *Covariates were those that correlated at r or r(s) ≥0.30 with outcomes: smoking status was controlled for perceived harm of VLNCs; age, e-cigarette use and smoking status were controlled for interest in trying VLNC; age, e-cigarette use and smoking status were controlled for intention to switch to e-cigarettes; the number of cigarettes smoked per day at session 1 was controlled for the number of cigarettes smoked per day at session 2. No covariates were controlled for the other outcomes.

• †Only tested among adults who smoked exclusively and adults who dual used (n=1443).

• EMM, Estimated Marginal Means; VLNC, very low nicotine cigarettes.