To attract internet users to an educational website on colorectal cancer, the US Centers for Disease Control and Prevention (CDC) posted advertisements on Yahoo!, an internet search engine used by 232 million people worldwide.1 The six week campaign included 12 advertisements in four formats (“east module,” “north banner,” “large rectangular,” and “streaming video large rectangular”—see bmj.com for examples) posted in locations throughout Yahoo!. Exposure to the advertisements was limited to health professionals and selected lay populations. Through a hyperlink, a software function that transfers users from one internet location to another,2,3 those who selected or “clicked” on an advertisement were transferred to the SFL website (Screen for Life: National Colorectal Cancer Action Campaign) (www.cdc.gov/cancer/screenforlife).4,5
The first phase of the campaign on Yahoo! lasted five weeks, from 29 April to 2 June 2002, and the advertisement space was paid for by the CDC. In the second phase of the campaign, which lasted one week (17-23 June 2002) the space was donated by Yahoo! as part of the “six weeks for the price of five” incentive deal that the CDC had accepted. This report analyses the traffic to the SFL website generated by the campaign, and the associated costs.