Table 2

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

Session1 outcomes/conditionsVLNC message, N=468E-cigarette message, n=484Combined message, n=476Control, n=473Univariate F statisticsAdjusted P value
Perceived absolute harm of VLNCs* (1–5 scale)
EMM (95% CI)4.09 (3.99 to 4.19)a3.81 (3.71 to 3.90)b4.03 (3.93 to 4.13)ac3.87 (3.78 to 3.97)bcF(3, 1687)=7.33, p<0.001, ηp2=0.0130.008
% of ‘don’t know’10.311.411.49.5
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=0.0010.70
% of ‘don’t know’12.914.013.713.4
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=0.0010.70
% of ‘don’t know’7.18.55.06.4
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=0.0050.40
% of ‘don’t know’9.55.67.56.5
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=0.0010.70
% of ‘don’t know’5.64.14.12.5
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=0.0030.56
% of ‘don’t know’
‘How interested are you in quitting smoking in the next 6 months?’4.26.14.22.3
‘How much do you plan to quit smoking in the next 6 months?’7.86.35.06.2
‘How likely are you to quit smoking in the next 6 months?’9.48.06.96.2
Session 2 Outcome/conditionsVLNC message, N=379E-cigarette message, n=383Combined message, n=374Control, n=374Univariate 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=0.0010.78
% of ‘don’t know’20.820.420.121.1
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=0.0020.70
  • 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.