Outcome variable | E-cigarette adverts (n=521) | Control adverts (n=536) | Test statistic | P values |

Perceived harm of occasional tobacco smoking | 508.69 | 546.84 | −2.129 | 0.033 |

Perceived harm of tobacco smoking in general | 525.10 | 529.84 | −0.435 | 0.664 |

Perceived harm of regular tobacco smoking | 531.91 | 524.18 | −0.512 | 0.609 |

Perceived disease risk (regular smoking) | 529.87 | 522.22 | −0.415 | 0.678 |

Perceived disease risk (occasional smoking) | 540.36 | 512.05 | −1.524 | 0.127 |

Tobacco smoking prevalence estimates | 521.96 | 513.12 | −0.477 | 0.634 |

Susceptibility to tobacco smoking | 42.4 | 37.9 | 2.515 | 0.113 |

Perceived harm of occasional e-cigarette use | 527.49 | 530.47 | −0.167 | 0.867 |

Perceived harm of e-cigarette use in general | 516.81 | 539.84 | −1.282 | 0.200 |

Perceived harm of regular e-cigarette use | 530.06 | 527.97 | −0.116 | 0.908 |

Perceived disease risk (regular e-cigarette use) | 520.34 | 527.56 | −0.389 | 0.697 |

Perceived disease risk (occasional e-cigarette use) | 523.22 | 526.74 | −0.193 | 0.847 |

E-cigarette use prevalence estimates | 523.19 | 513.90 | −0.501 | 0.616 |

Susceptibility to e-cigarette use | 50.1 | 49.8 | 0.015 | 0.902 |

Appeal of adverts | 426.32 | 628.80 | −10.797 | <0.001 |

Interest in buying and trying advertised product | 393.83 | 660.39 | −14.298 | <0.001 |

For all outcome variables, the test statistic corresponds to the

*Z*value from the Mann-Whitney U analyses (with corresponding mean ranks shown for each experimental group), except for the variables susceptibility to smoking and e-cigarettes use which are binary variables and are denoted by percentages summarised using the*X*^{2}test statistic.