Baseline characteristics of study participants
| Variables: independent | Mean/percentage | SD | n |
| Demographics | |||
| Age | 16.06 | 1.39 | 1610 |
| 14 | 0.18 | 0.38 | 1610 |
| 15 | 0.20 | 0.40 | 1610 |
| 16 | 0.20 | 0.40 | 1610 |
| 17 | 0.22 | 0.41 | 1610 |
| 18 | 0.20 | 0.40 | 1610 |
| Female | 0.49 | 0.50 | 1610 |
| Parents have some college education | 0.67 | 0.47 | 1610 |
| Free or reduced lunch recipient | 0.48 | 0.50 | 1610 |
| School satisfaction scale | 6.4 | 2.74 | 1610 |
| Race/ethnicity | |||
| American Indian or Alaska native | 0.02 | 0.14 | 1610 |
| Asian | 0.05 | 0.22 | 1610 |
| Black | 0.09 | 0.29 | 1610 |
| Multiracial | 0.07 | 0.26 | 1610 |
| Native Hawaiian or Pacific Islander | 0.01 | 0.12 | 1610 |
| White | 0.75 | 0.43 | 1610 |
| Hispanic | |||
| Hispanic | 0.20 | 0.40 | 1610 |
| Urbanicity | |||
| Rural | 0.23 | 0.42 | 1610 |
| Suburban | 0.54 | 0.50 | 1610 |
| Urban | 0.23 | 0.42 | 1610 |
| JUUL and e-cigarette use | |||
| Ever heard or seen JUUL | 0.89 | 0.31 | 1610 |
| Ever heard or seen e-cigarette | 0.93 | 0.26 | 1610 |
| Never heard or seen JUUL | 0.11 | 0.31 | 1610 |
| Never heard or seen e-cigarette | 0.07 | 0.26 | 1610 |
| Ever tried combustible cigarette | 0.30 | 0.46 | 1610 |
| Ever tried e-cigarette | 0.38 | 0.48 | 1496 |
| Ever tried JUUL | 0.37 | 0.37 | 1439 |
| Parents use combustible cigarette | 0.26 | 0.44 | 1610 |
| Parents use e-cigarette | 0.09 | 0.28 | 1610 |
| Parents use JUUL | 0.04 | 0.19 | 1610 |
| Variables: dependent | Mean | SD | n |
| JUUL risk perception scales* | |||
| Lung cancer risk | 7.29 | 2.84 | 8050 |
| Second-hand vapour risk | 6.48 | 3.21 | 8050 |
| Average risk of addiction | 7.11 | 2.85 | 8050 |
| Healthiness | 2.11 | 2.78 | 8050 |
| e-Cigarette risk perception scales* | |||
| Lung cancer risk | 7.13 | 3.02 | 8050 |
| Second-hand vapour risk | 6.49 | 3.19 | 8050 |
| Average risk of addiction | 6.94 | 2.87 | 8050 |
| Healthiness | 1.87 | 2.70 | 8050 |
For dichotomous variables, the mean can be interpreted as the percentage of the variable in the sample. The total sample size is 1610 respondents. Sample size for ‘ever tried’ variables is conditional on a ‘yes’ response to ‘ever heard’ variables and thus smaller than the full sample.
*The data is transformed into a long format for analysis, and the dependent variables (risk dimensions) presented in this table are averaged across all five possible flavours for each respondent. Therefore, there are 8050 observations (5 flavour values for each 1610 respondents).