Newswise — One of the first large-scale analyses of how people share knowledge on Yahoo Answers has found that participants use the site to exchange advice and opinions, in addition to technical expertise.

"There are gobs and gobs of useful information on the web," said Lada Adamic, an assistant professor at the University of Michigan School of Information and first author of the study. "Search tools allow one to, in principle, access a fair portion of it with relative ease. Yet, just as one may turn to a colleague for an answer to a question rather than search through a book, millions of individuals are flocking to online question/answer forums to seek answers directly from others. Part of the reason is the social aspect of online question/answer forums."

Recent School of Information doctoral graduate Jun Zhang will present the research April 23 at the WWW2008 conference in Beijing.

With approximately 23 million resolved questions in the system at the time of this study, Yahoo Answers is by far the largest English-language site devoted to questions and answers.

Adamic, along with the School of Information's Mark Ackerman and other colleagues, analyzed one month of activity on the Yahoo Answers site: 1.2 million questions by 495,414 people and 8.5 million answers by 433,402 people. The askers and answerers overlapped, with 211,372 people doing both. The level of activity among users varied. Most users participated only in a question or two, while some were involved in hundreds.

Anyone who registers can ask or answer questions at Yahoo Answers. The site organizes questions by category, and the researchers examined 300 of the roughly 1,000 categories---more than 91 percent of the content on the site. They looked at jokes and riddles; philosophy, religion and politics; marriage and divorce; physics; programming; chemistry; and celebrities, to name a few.

The study organized these categories into three groups based, in part, on the types of question asked and the average number of replies per question.

In the group that includes the biology, repairs and programming categories, inquiries sought factual answers. These questions tended to receive fewer replies. Adamic said she wasn't surprised. Once someone gives the right answer, there's no real need for others to respond.

Categories such as fashion, baby names, fast food and cats and dogs included mainly advice and common-sense expertise requests for which there wasn't a single factual answer. These categories received comparatively long answer threads.

Categories like politics and religion/spirituality had mostly discussion-forum questions seeking opinion. These tended to attract many answers as well.

"Who is the better actress: Angelina Jolie or Jennifer Aniston?" from the celebrities category is an example of such a question. It came up twice in the month of data the researchers examined, garnering 33 and then 50 answers.

The researchers found these types of questions particularly interesting, given the way Yahoo Answers is set up. Participants can't have the sort of broad-based conversations that are possible in other online media such as newsgroups. Those who ask a question in Yahoo Answers can survey the responses, tag the best answer and post one brief reply.

"A lot of the use of Yahoo Answers is being driven by these constrained kinds of discussions," said Ackerman, associate professor at the U-M School of Information. "People are working against the medium. They're creating a new response pattern. Perhaps there's a new online genre that's particular to Yahoo Answers."

In the fact-based categories, researchers found that the questions were relatively simple. Math and science categories, for example, appeared to be dominated by high school students seeking easy solutions to their homework. Of 100 randomly selected questions from the programming category, only one required an expertise level beyond one year of programming experience.

The knowledge shared in Yahoo Answers is very broad in several senses, but generally not very deep, the study shows.

The U-M researchers discovered the formula for getting an answer chosen as the best. Users who specialized in answering questions in one particular technical category and gave longer answers tended to have theirs chosen as best more often.

"Askers prefer longer replies, whether it is a question about marriage, wrestling or science," Adamic said.

Ackerman and Adamic are also faculty members in the U-M Department of Electrical Engineering and Computer Science.

Their study is called "Knowledge sharing and Yahoo Answers: Everybody knows something."

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WWW2008 conference in Beijing