知识共享与众包-Harvard：Knowledge-Sharing-and-Crowdsourcing.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,*,Knowledge Sharing and,Crowdsourcing,Xiaolu Yu,11/12/2008,Web 2.0,Online reviews:,Social networking:,Social media sites:,Tagging/folksonomies systems:,Online encyclopendia:,Online blogs:,Online question-answer forums:,CrowdSourcing forums:,This is the next generation of search.Its kind of a collective brain of searchable database of everything everyone knows.It is a culture of generosity.The fundamental belief is everyone knows something.,-Yahoo Research,Knowledge Sharing,Online,encloypendia,Online question-answer forum,CrowdSourcing,Question-Answer Forum,Characteristics,General purpose,Open to public,Large question-answer repository,Examples,Yahoo Answers,Google Answers,Baidu,Knows,Yahoo!Answers,More than 21 million unique users in the U.S.and 90 million worldwide,Largest knowledge-sharing community on the Web,Anyone can ask and answer questions on any topic,Connecting people to the information theyre seeking with those who know it,Providing a way for people to share their experience and insight,Scoring System,Action,Points,Begin participating on Yahoo!Answers,One Time:100,Ask a question,-5,Choose a best answer for your question,3,No Best Answer was selected by voters on your question,Points Returned:5,Answer a question,2,Deleting an answer,-2,Log in to Yahoo!Answers,Once daily:1,Vote for a best answer,1,Vote for No best answer,0,Have your answer selected as the best answer,10,Receive a thumbs-up rating on a best answer that you wrote(up to 50 thumbs-up are counted),1 per thumbs-up,Levels,Level,Points,Questions,Answers,Comments,Stars,Ratings,Votes,7,25,000+,*,unlimited*,100,unlimited,100,6,10,000-24,999,*,unlimited*,100,unlimited,100,5,5,000-9,999,*,unlimited*,100,unlimited,80,4,2,500-4,999,20,80,40,100,unlimited,80,3,1,000-2,499,15,60,30,100,unlimited,60,2,250-999,10,40,20,100,unlimited,40,1,1-249,5,20,10,10,0,20,*,All limitations are per day,Every category rates the top ten best answerers based on the number of their best answers(chosen by askers or voters).,People can either search for questions/answers they are interested in,or actually ask a question,Category Clustering,How has one place youve traveled to changed your life?,Travel has had a huge impact on me before,opening my eyes and changing my perspective.Some places Ive been have affected me more than others.Where have you been that has changed you and how?,Best Answer-Chosen by Asker,I dont think of simply one place changing my perspective as I have traveled the world.What I believe travel does is to afford a most excellent education and to(no pun)broaden horizons.To have the opportunity to see and embrace other peoples lifestyles and cultures is wonderful.Wherever we have been,we have found wonderful people,many of whom have become dear friends.These new found friends make travel meaningful.Places may be interesting,but it is the people that make travel worthwhile.,A typical bad answer,Yes.It made me realize that females are equally stuck-up all over the country.,(Still earning 2 points!Noise introduced),Discussion forum,What do you do with a 15month old girl who holds her breath till she gets what she wants?,Best Answer-Chosen by Asker,Youve gotten a lot of bad answers!I agree that you should*usually*not give in to your child.What my doctor told me to do when my daughter used to hold her breath(she passed out more than 10 times,including in a store once)was to lay her down so that she would be safe and then leave the room.It is one of the hardest things I have ever done,but it does work.,The most difficult thing to understand is that nothing bad will actually happen to your child if shes lying down at the time(if she isnt,she could fall and get hurt).I still find it hard to see a child holding his or her breath,despite knowing this.,Seeking and providing advice,and commonsense expertise,Is Earths solar eclipse unique in the solar system?,Can scientific observation and theory prove if are there any other planets in the solar system which have moons that would allow us to observe the exact same effect as our perfect solar eclipse here on Earth?If not,why not?,Best Answer-Chosen by Voters(,82%,9 Votes),Not possible on Mercury or Venus as they dont have any moons.,Phobos,and,Diemos,the two Martian moons,are quite tiny(less than 50,kilometres,in diameter)and it seems unlikely that solar eclipses could occur on Mars,Jupiter has 63 moons,Saturn 56,Uranus 27,Neptune 13 and Pluto 3 at the latest census.165 moons around 7 planets in all,Plus there are at least 80 moons around asteroids and minor planets,The asteroid 87 Sylvia has two moons.Table of Moons by diameter in,kilometres,Factual Answers,How to identify experts?,How to decide if an answer is worthwhile?,What does the quality of questions mean to the quality of answers and behaviors of users?,Why Google Answers(offering real money incentive)did not survive?,How would users behaviors change if real money awards are introduced in to the system?,Network Structure Analysis,Best Answer Selection and Prediction,What are the criteria for best answer selection?,Factual-answer categories objective,Other categories subjective,What are the problems with selecting just one best answer?,One best answer per question,Answer-to-question ratio,Noise,What metrics are most predictive of best answers?,Reply length,Number of competing answers,Track record of the user(most significant for technically focused categories),Discussion,How to identify experts?,How to decide if an answer is worthwhile?,What does the quality of questions mean to the quality of answers and behaviors of users?,Is depth sacrificed for breadth?,How to discern good answers that were not rated as the best answers?,Why Google Answers(offering real money incentive)did not survive?,Harper et al.(2008)found that the system that offered money(Google Answers)yielded better answers.,How would users behaviors change if real money awards are introduced in to the system?,Crowdsourcing,Crowdsourcing,is a neologism for the act of taking a task traditionally performed by an employee or contractor,and outsourcing it to an undefined,generally large group of people,in the form of an open call.,The term has become popular with business authors and journalists as shorthand for the trend of leveraging the mass collaboration enabled by Web 2.0 technologies to achieve business goals.,Crowd Sourcing Examples and differences,Taskcn,eLance,TopCoder,Google Answers,Crowd Sourcing Examples and differences,eLance,and,TopCoder,:Tasks are attempted after the requester chooses a provider or a team of providers based on his/their credentials and proposals.,Google Answers:participations are limited to expert answerers recruited;answerers would have exclusive locks on the tasks for a period of time.,Taskcn,:users submit their work directly(new,Taskcn,offers multiple approaches based on the difficulty and complexity of tasks.),T,1.7 million registered users,In less than 2 years,requested solutions for nearly 3100 tasks and 543,000 solutions proposed,A user offers a monetary award for a question or task and other users provide solutions to compete for the award.,The website plays the role of the third party,by collecting the money from the requester and distributing the award to the,winner(s,)who is(are)decided by the requester.,The website takes a small portion of the award as a service fee.,Socially stable:,a core group of users,who repeatedly propose and win,Incentivized mechanism:Potential monetary award encourages peoples participation.,Users are Learning over Time,Submit later,Choose less popular tasks,Choose Tasks with higher winning odds,Raise award expectation,However,average users fail to improve.,Submit Later,Winners consistently submit later than non-winners over time,implying greater effort.,Combination of Multiple Strategies by Serious Users,Higher winning probability,Less popular tasks,Higher expected award,Tasks requiring greater skill,Avoid tasks of higher workload,Workload is negatively correlated with award.,Rich Getting Richer?,On average,users do not increase(decrease)their chances of winning although they implement strategies.,In contrast,a very small core of successful users manage to win multiple tasks as well as to increase their win-to-submission ratio over time.,Reputation enhancement or learning process?,Incentive,task complexity&user strategy,Why incentive would change users participation and strategy?,It encourages users to contribute expertise beyond simple question answering,as might occur on no-fee sites such as Yahoo!Answers.,The task submitted must be necessarily of relatively low complexity and effort since given no guarantee of awards.,(New,Taskcn,feature):In the case that task is attempted after the requester makes his choice,the tasks are relatively more complex.,Winning Strategy,Target group:a group of winners who get more efficient at winning over time.,Observation:quickening in the succession of wins,Winning Strategy,Successful in selecting tasks of lower popularity than those chosen by average users from their first,attemps,.,Winning Strategy,Successfully selecting less popular tasks from the very first attempts,Always submitting later than others,Winners are better at starting and sticking with such strategies that will improve their chances of winning.,Core Group Contribution,A large fraction of winning task solutions is contributed by a small core group of individuals.,Such,skewness,of contribution to Internet peer production systems have been widely observed.,Wikipedia,Participation is open to anyone,but a large portion of the content is contributed by a small minority of the participants.,Design Implications,Identify the core group of winners early,Incentivize the core group(if a core group is necessary),Drive large number of prospective users towards a site,Make task awards and skills and level required by the tasks commensurate,