case_images: PMC1550633_01
case_images: Invitation email written in hypertext markup language used in Study 1
case_images: jmir_v7i1e6_fig1.jpg
case_images: PMC1550633_01_jmir_v7i1e6_fig1.jpg
case_images: figure1
case_images: In the first group, emails indicated that the first 30 respondents would receive a Can $20 electronic gift certificate for use at an online bookstore if they went to the Smoking Zine website and responded to a short online survey (Figure 1). In both groups, the invitation email was written in hypertext markup language (HTML) and contained images including a prominent banner depicting a Can $20 gift certificate, a logo of the University of Toronto, and screen images of the front page of the Smoking Zine and the CyberIsle websites (Figure 1).
case_images: Reminder email written in plain text used in Study 1
case_images: jmir_v7i1e6_fig2.jpg
case_images: PMC1550633_01_jmir_v7i1e6_fig2.jpg
case_images: figure2
case_images: The reminder email messages were fully text-based (not HTML-based) and no graphical images were used (Figure 2).