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Judit Bar-ilan and Ana Echerman’s “The Anthrax Scare and the Web: A Content Analysis of Webpages Linking to Resources on Anthrax”

Research Summary

The Internet makes finding information fast and easy, particularly in the workplace.  Yet few people fully understand how subject-related content is presented on the web.  By understanding how the public uses search results on a specific topic, risk communicators can improve the way they craft and share both online and other messages.

Judit Bar-Ilan and Ana Echerman of Bar-Ilan University and The Hebrew University of Jerusalem conducted a study focused on developing “a method for characterizing the page and linking patterns related to dramatic events on the Web.”  For the purposes of this study, the authors focused on the anthrax attacks which occurred in the United States shortly after 9/11.

The study found that during the timeframe of the attacks people increasingly turned to the Internet for anthrax-related information. Anthrax was Google’s fifth overall search in 2001, reaching first place during October 2001.  There was a corresponding increase in traffic to the anthrax pages on the Web site of the Centers for Disease Control and Prevention (CDC). These CDC pages received 515,000 unique visits during the week of October 14, 2001, a 118% increase from the week before.

With this increase in anthrax-related Web traffic, the authors sought to identify trends among pages that link to authoritative Web sites on anthrax (i.e. CDC, Office of the Secretary of Defense, Journal of the American Medical Association, etc.).  They classified pages by the following categories: page type, page topic, topic of the source section where the link is located, content producer. Links were also included, and sorted into the categories of link type and link placement.  Other information about each page was also captured, such as language, most recent update, and domain name.

The results of this study indicate that the anthrax attacks increased the number of anthrax-related searches and news coverage, but it did not have a statistically significant impact on the amount of factual information available on the Web.  The study found that “content producers often preferred to compose lists of links to resources on anthrax rather than produce their own original content.”  Content producers also tended to link to U.S. government resources more than they linked to other pages.

The most common page type was news items, which are briefings posted on websites other than where the original news story appeared.  It should be noted that this finding indicates that consumers may be relying on second and third-hand sources for information, rather than upon an original or authoritative source.

While the results of this study will be interesting to a variety of readers, the methods employed by the authors may be of the most use to risk communicators because they outline a process for determining how consumers are encountering a particular topic on the Internet. This process includes such questions as: What types of pages are providing links to the topic?  What types of links are being provided?  The answers to these questions could prove useful to a risk communicator in determining how and where to post information online.


Bar-Ilan, J., Echerman, A. The anthrax scare and the Web: A content analysis of Web pages linking to resources on anthrax. Scientometrics 2005; 63(3); 443-462.

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