Table 1.

Interview guide.

Construct	Elicitation question
Knowledge	What is an e-cigarette? What kind of brands of e-cigarettes have   you heard of? Have you ever seen an ad for e-cigarettes? If   so, where? Television, magazines, other? Do you know of any other names for e-   cigarettes?
Attitudes	How do you feel about the idea of   undergraduates using e-cigarettes? What do you like/dislike about e-cigarettes? What do you enjoy/hate about e-cigarettes? What are your opinions when you see   someone using an e- cigarette? Does it depend on the location?
Perceived benefit/   perceived advantages	What are some advantages of using e-   cigarettes? What are the benefits that might result from   using e-cigarettes?
Perceived threat/   perceived disadvantages	What are some disadvantages of using e-   cigarettes? What are the negative health effects that   might result from using e-cigarettes? Do you think e-cigarettes are less/more   harmful than conventional cigarettes?   Why?
Perceived barriers	What kinds of barriers do you perceive to   using e-cigarettes?
Perceived norms	Who, which people or groups, might   approve or support of your use of e-   cigarettes? Who, which people or groups, might   disapprove of your use of e-cigarettes?
Perceived self-efficacy	If you want to use e-cigarettes, how certain   are you that you can?