Health information written by a doctor is rated as more credible when it appears on a Web site than in a blog or a homepage, according to a study of college students. The findings highlight the relative importance（相对重要性） of different online sources to people who seek health information on the Internet.

"Most people look for health information online by keying disease symptoms（症状） into various search engines," said S. Shyam Sundar, distinguished professor（特聘教授） of communications, Penn State. "But the results of that search could range from experts at the Mayo Clinic to somebody's personal blog."

Sundar and his colleague Yifeng Hu, lead author and assistant professor of communications, College of New Jersey, Ewing, N.J., study how people evaluate and act on online health information.

"We are looking at accuracy and believability（可信度） ," explained Sundar. "We want to see how people act on the advice they receive, and whether they recommend（劝告，推荐） it to others or forward it to friends online."

Researchers found that study participants were more likely to believe -- and make use of -- information on a website from a source identified as an expert than from a layperson（外行） . Health information on the websites of TV, radio, and newspapers was not included in the study.

Participants also believed that editors and moderators help websites present accurate and complete information. Blogs, homepages, and social networking sites were seen as lacking such gatekeeping. The findings appear in the February issue of Communication Research.

Sundar and Hu presented 555 college students with screenshots of one of two health articles, attributed either to a doctor or to a layperson. Students received these articles as either from a formal website, individual homepage, a blog, a bulletin board -- a chat site where people can post messages -- or were simply told that they came from the Internet.

The first article discouraged the use of sunscreen（遮光剂，防晒霜） to avoid Vitamin D deficiency, while the second advocated（提倡，主张） the consumption of raw milk over pasteurized milk（巴氏杀菌奶） .

"We wanted to find out if users differentiate between various sources of online information and how that choice impacts their decisions," said Sundar. "The health topics were controversial enough to raise questions of credibility among readers."

Statistical analyses of student questionnaires（问卷，调查表） suggest that screenshots of both health topics were seen as significantly more reliable when attributed to a doctor and featured on a website rather than on a blog, individual homepage or a bulletin board.

"It tells us that young people are actually differentiating between different online sources when evaluating health information on the Internet," said Sundar.

Students were also significantly more likely to follow up on the advice they had received through websites and bulletin boards -- compared to blogs and homepages -- by acting on it and sharing it with friends.

Sundar believes that additional use of expert sources could help online bulletin boards gain greater credibility.

"It is the future of how health information will be distributed over the Internet," said Sundar. "If doctors are serious about disseminating（散播，宣传） health information, they should do it on a bulletin board instead of a homepage."