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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.
From the moment the first advertisement was posted on Yahoo! we tracked the number of times advertisements were displayed (“audience exposures”) and the number of visits to the SFL website that resulted from use of the hyperlink in the advertisements. For comparison data, we also monitored daily visits to the website for three months before and after the campaign, so the whole monitoring period lasted 1 March to 31 August. We tracked campaign costs using vendor invoices.
During the six week campaign, the advertisements were displayed 29 673 418 times. Of these audience exposures, the CDC paid for 25 495 000 (first phase); Yahoo! donated the rest (second phase).
In total, 26 697 visits to the SFL website resulted from use of the hyperlink in the advertisements. The mean number of daily visits during the pre-campaign period was 418; that number tripled (to 1282) during the first (CDC funded) phase and doubled (to 992) during the second (donation) phase (figure). Visits resulting from use of the hyperlink in the advertisements accounted for half of the total website traffic during the six week campaign. By using a “bookmark” or hyperlink established on a personal computer, some visitors continued to enter the SFL website through the hyperlink in the advertisments during periods when the advertisements were not posted on Yahoo!; bookmarked entries accounted for 6% of visits during the break between the two campaign phases and 1% of visits during the post-campaign period.
The total cost of the campaign was $64 627 (£35 400; €52 500)—$22 127 for converting existing SFL materials into 12 internet advertisements and $42 500 for advertising space on Yahoo!. Thus, the total cost per audience exposure was $0.002 and the total cost per visit resulting from use of the hyperlink in the advertisements was $2.42.
The campaign generated more than 26 000 visits to the SFL website at a cost of $2.42 (£1.33; €1.97) per visit. Campaign costs were minimised by developing advertisements that paralleled existing SFL materials—for example, we converted SFL's television public service announcements and print materials into internet advertisements. Also, at the time of this campaign, advertising space on Yahoo! was relatively inexpensive, and Yahoo! donated millions of audience exposures to the campaign as an incentive to secure the account. Online advertisements are a viable strategy to attract internet users to health promotion websites.
We thank Anil Ninan and Denise H Farmer for their help in extracting the data analysed from log files of the US Centers for Disease Control and Prevention's web servers and Lucy A Peipins, Steve S Coughlin, Mary C White, Kevin T Brady, and Peter L Taylor for their feedback on early drafts of this article.
Contributors: All authors designed the study. CPC analysed the data and wrote the manuscript. All authors are guarantors.
Funding: The study was funded by the US Centers for Disease Control and Prevention.
Competing interest: CSF is employed by Yahoo!, the for-profit internet search engine that CDC had a contract with during this campaign. CSF's professional compensation includes Yahoo! stock. The results of this study could potentially benefit Yahoo! by attracting new advertisers.
Ethical approval: Not needed.