GroupLens Research

In 1992, John Riedl and Paul Resnick attended the

CSCW conference

together. After they heard keynote speaker Shumpei Kumon talk

about his vision for an information economy,

{{cite conference|last=Kumon|first=Shumpei|year=1992|title=From wealth to wisdom: a change in the social paradigm|conference=Computer Supported Cooperative Work|publisher=ACM Press|page=3|doi=10.1145/143457.371587|isbn=0-89791-542-9|book-title=Proceedings of the 1992 ACM conference on Computer-supported cooperative work}} they began working on a collaborative filtering

system for Usenet news. The system collected ratings from Usenet readers and used those ratings to predict how much other readers would like an article before they read it. This recommendation engine was one of the first automated collaborative filtering systems in which algorithms were used to automatically form predictions based on historical patterns of ratings.

{{cite book|title=Knowledge in a Social World|last=Goldman|first=Alvin I|publisher=Oxford University Press|year=1999|isbn=978-0-19-823820-1|doi=10.1093/0198238207.001.0001|quote=Another possibility is "social filtering" systems, such as GroupLens.|author-link=Alvin Goldman}}

The overall system was called the "GroupLens" recommender, and the servers that collected the ratings and performed the computation were called the "Better Bit Bureau". This name was later dropped after a request from the Better Business Bureau. "GroupLens" is now used as a name both for this recommender system, and for the research lab at the University of Minnesota.

A feasibility test was done between MIT and

the University of Minnesota and a research paper was published including

the algorithm, the system design, and the results of the feasibility

study, in the CSCW conference of 1994.

{{cite conference|last=Resnick|first=Paul|author2=Iacovou, Neophytos|author3=Suchak, Mitesh|author4=Bergstrom, Peter|author5=Riedl, John|year=1994|title=GroupLens: an open architecture for collaborative filtering of netnews|conference=Computer Supported Cooperative Work|publisher=ACM Press|pages=175–186|doi=10.1145/192844.192905|isbn=0-89791-689-1|book-title=Proceedings of the 1994 International ACM Conference on Computer Supported Cooperative Work|doi-access=free}}

In 1993, Riedl and Resnick invited Joseph Konstan to join the

team. Together, they decided to create a higher-performance

implementation of the algorithms to support larger-scale deployments.

In summer 1995 the team gathered

Bradley Miller, David Maltz,

Jon Herlocker, and Mark Claypool for "Hack Week" to create

the new implementation, and to plan the next round of experiments.

{{cite journal|last1=Borchers|first1=Al|last2=Herlocker|first2=Jon|last3=Konstan|first3=Joseph|last4=Riedl|first4=John|date=April 1998|title=Ganging up on Information Overload|journal=Computer|volume=31|issue=4|pages=106–108|doi=10.1109/2.666847|issn=0018-9162}}

In the Spring of 1996, the first workshop on

collaborative filtering was put together by Resnick and

Hal Varian at the University of California, Berkeley.{{cite web

| url = http://www2.sims.berkeley.edu/resources/collab/

| title = Collaborative Filtering

| date = March 16, 1996

| access-date = 2009-12-30

| archive-date = 2013-08-17

| archive-url = https://web.archive.org/web/20130817042907/http://www2.sims.berkeley.edu/resources/collab/

| url-status = dead

}}

There, researchers from projects around the US

that were studying similar systems came together to share ideas and

experience.

In the summer of 1996, David Gardiner, a former Ph.D. student of Riedl's, introduced John Riedl to Steven Snyder. Snyder had been an early employee at Microsoft, but left Microsoft to come to Minnesota to do a Ph.D. in Psychology. He realized the commercial potential of collaborative filtering, and encouraged the team to found a company in April 1996. By June, Gardiner, Snyder, Miller, Riedl, and Konstan had incorporated their company, and by July they had their first round of funding, from Hummer Winblad Venture Partners

venture capital company.

{{cite web

| url = http://news.minnesota.publicradio.org/features/199912/01_newsroom_dotcom/images/dotcom.pdf

| title = Minnesota in the .Com Age

| publisher = Minnesota Public Radio

| year = 1999

| access-date = 2009-12-30

}}

Net Perceptions went on to be one of the leading companies in

personalization during the Internet boom of the late 1990s, and stayed

in business until 2004.

{{cite web

| url = http://web.mit.edu/newsoffice/1999/ecomm-0519.html

| title = Firms honored at e-commerce awards

| publisher = MIT

| date = May 19, 1999

}}

{{Citation

| last = Dragan

| first = Richard

|date=January 2001

| title = Net Perceptions for E-commerce 6.0

| periodical = PC Magazine

| url = https://www.pcmag.com/article2/0,2704,107446,00.asp

}}

Based on their experience, Riedl and Konstan wrote a book about the lessons learned from deploying recommenders in practice.

{{cite book

| title = Word of Mouse: The Marketing Power of Collaborative Filtering

| last1 = Riedl

| first1 = John

| last2 = Konstan

| first2 = Joseph

| last3 = Vrooman

| first3 = Eric

|date=August 2002

| publisher = Grand Central

| isbn = 978-0-7595-2727-0

}}

Recommender systems have since become ubiquitous in the online world, with leading vendors such as Amazon and Netflix deploying highly sophisticated recommender systems.

{{cite news

| url = https://www.wsj.com/articles/SB121633741917263835

| title = Technology Gets Personal

| first = Steven

| last = Zeitchik

| newspaper = The Wall Street Journal

| date = July 18, 2008

| page = W9

| access-date = 2009-12-23

}}

Netflix even offered a $1 million prize for improvements in recommender technology.

{{cite news

| url = https://www.nytimes.com/2006/10/02/technology/02iht-netflix.2998832.html

| title = Netflix offers cash for good suggestions

| first = Katie

| last = Hafner

| author-link = Katie Hafner

| newspaper = The New York Times

| date = October 2, 2006

| access-date = 2009-12-23

}}

When

the EachMovie

{{cite conference

| url = https://archive.org/details/webintelligencer0000wi20/page/438

| title = An Adaptive Recommendation System with a Coordinator Agent

| first = Myungeun

| last = Lim

| author2 = Kim, Juntae

| year = 2001

| conference = Asia-Pacific Conference on Web Intelligence

| book-title = Proceedings of the First Asia-Pacific Conference on Web Intelligence: Research and Development

| series = Lecture Notes in Computer Science

| volume = 2198/2001

| publisher = Springer Berlin/Heidelberg

| pages = [https://archive.org/details/webintelligencer0000wi20/page/438 438–442]

| isbn = 978-3-540-42730-8

| doi = 10.1007/3-540-45490-X_56

| access-date = 2009-12-30

}}

site closed in 1997, the researchers behind it released

the anonymous rating data they had collected, for other researchers

to use. The GroupLens Research team, led by Brent Dahlen and Jon

Herlocker, used this data set to jumpstart a new movie recommendation

site called MovieLens which has been a very visible research platform, including a detailed discussion in a New Yorker article by

Malcolm Gladwell,

{{cite journal

|url=http://www.gladwell.com/1999/1999_10_04_a_sleeper.htm

|title=Annals of Marketing: The Science of the Sleeper: How the Information Age Could Blow Away the Blockbuster

|first=Malcolm

|last=Gladwell

|author-link=Malcolm Gladwell

|journal=New Yorker

|volume=75

|issue=29

|date=October 4, 1999

|pages=48–55

|access-date=2009-12-29

|url-status=dead

|archive-url=https://web.archive.org/web/20091230235916/http://gladwell.com/1999/1999_10_04_a_sleeper.htm

|archive-date=December 30, 2009

}}

and a report in a full episode of ABC Nightline.

{{cite web

| last = Krulwich

| first = Robert

| author-link = Robert Krulwich

| date = December 10, 1999

| title = ABC Nightline: Soulmate

| publisher = ABC

| url = http://tvnews.vanderbilt.edu/program.pl?ID=649063

}}

Between 1997 and 2002 the group continued its research on

collaborative filtering, which became known in the community by the

more general term of recommender systems. With Joe Konstan's expertise in user interfaces,

{{cite journal

| url = http://bulletin.sigchi.org/2003/july/sigchi-2003-election-results/

| title = SIGCHI 2003 Election Results

| journal = SIGCHI Bulletin

| volume = 35

| issue = 3

| date = July–August 2003

| access-date = 2010-01-04

}}

{{cite journal

| url = http://bulletin.sigchi.org/2004/march/presidents-report-advancing-the-field/

| title = President's Report: Advancing the Field

| first = Joseph

| last = Konstan

| journal = SIGCHI Bulletin

| volume = 36

| issue = 2

| date = March–April 2004

| access-date = 2009-12-30

}}

the team began exploring interface issues in recommenders, such as explanations,

{{cite conference|last=Herlocker|first=Jon|author2=Konstan, Joseph|author3=Riedl, John|year=2000|title=Explaining Collaborative Filtering Recommendations|conference=Computer Supported Cooperative Work|publisher=ACM Press|pages=241–259|doi=10.1145/358916.358995|isbn=1-58113-222-0|conference-url=http://www.grouplens.org/node/220|book-title=Proceedings of the 2000 ACM conference on Computer supported cooperative work}}

and meta-recommendation systems.

{{cite conference

| url = http://www.grouplens.org/node/185

| title = Meta-recommendation Systems: User-controlled Integration of Diverse Recommendations

| first = J. Ben

| last = Schafer |author2=Konstan, Joseph |author3=Riedl, John

| year = 2002

| conference = Conference on Information and Knowledge Management

| conference-url = http://www.csee.umbc.edu/cikm/2002/

| book-title = Proceedings of the eleventh international conference on Information and knowledge management

| publisher = ACM Press

| pages = 43–51

| isbn = 1-58113-492-4

| doi = 10.1145/584792.584803

| access-date = 2010-01-06

| url-access = subscription

}}

In 2002, GroupLens expanded into social computing and online communities with the addition of Loren Terveen, who was known for his research of social recommender systems such as PHOAKS.

{{cite book

| title = From Usenet to CoWebs: Interacting with Social Information Spaces

| editor1-last = Lueg

| editor1-first = Christopher

| editor2-last = Fisher

| editor2-first = Danyel

| publisher = Springer

| year = 2003

| isbn = 978-1-85233-532-8

}}

{{cite journal

| first1 = Loren

| last1 = Terveen

| first2 = Will

| last2 = Hill

| first3 = Brian

| last3 = Amento

| first4 = David

| last4 = McDonald

| first5 = Josh

| last5 = Creter

| title = PHOAKS: a system for sharing recommendations

| journal = Communications of the ACM

| volume = 40

| issue = 3

|date=March 1997

| pages = 59–62

| issn = 0001-0782

| doi = 10.1145/245108.245122

| citeseerx = 10.1.1.103.8264

| s2cid = 207201836

}}

In order to broaden the set of research ideas and tools they used,

Riedl, Konstan, and Terveen invited colleagues in social psychology

(Robert Kraut and Sara Kiesler, of the

Carnegie Mellon Human Computer Interaction Institute), and

economic and social analysis (Paul Resnick and

Yan Chen of the

University of Michigan School of Information) to collaborate. The

new, larger team adopted the name CommunityLab, and looked

generally at the effects of technological interventions on the

performance of online communities. For instance, some of their

research explored technology for enriching conversation systems,

{{cite conference

| url = http://www.grouplens.org/node/107

| title = Talk amongst yourselves: inviting users to participate in online conversations

| first1 = F. Maxwell

| last1 = Harper

| first2 = Dan

| last2 = Frankowski

| first3 = Sara

| last3 = Drenner

| first4 = Yuqing

| last4 = Ren

| first5 = Sara

| last5 = Kiesler

| first6 = Loren

| last6 = Terveen

| first7 = Robert

| last7 = Kraut

| first8 = John

| last8 = Riedl

| year = 2007

| conference = International Conference on Intelligent User Interfaces

| conference-url = http://iuiconf.org/

| book-title = Proceedings of the 12th international conference on Intelligent user interfaces

| publisher = ACM Press

| pages = 62–71

| isbn = 978-1-59593-481-9

| doi = 10.1145/1216295.1216313

| access-date = 2009-12-29

| url-access = subscription

}} while other research explored the personal, social, and economic

motivations for user ratings.

{{cite conference

| url = http://www.grouplens.org/node/135

| title = An Economic Model of User Rating in an Online Recommender System

| first1 = F. Maxwell

| last1 = Harper

| first2 = Xin

| last2 = Li

| first3 = Yan

| last3 = Chen

| first4 = Joseph

| last4 = Konstan

| year = 2005

| conference = 10th International Conference on User Modeling

| conference-url = http://gate.ac.uk/conferences/um2005/um05.html

| book-title = User Modeling 2005 Proceedings

| series = Lecture Notes in Computer Science

| volume = 3538

| publisher = Springer

| pages = 307–316

| isbn = 978-3-540-27885-6

| doi = 10.1007/11527886_40

| access-date = 2009-12-29

| url-access = subscription

}}

{{cite conference

| url = http://www.grouplens.org/node/124

| title = Motivating Participation by Displaying the Value of Contribution

| first = Al Mamunur

| last = Rashid

|author2=Ling, Kimberly |author3=Tassone, Regina D. |author4=Resnick, Paul |author5=Kraut, Robert |author6= Riedl, John

| year = 2006

| conference = ACM SIGCHI Conference on Human Factors in Computing Systems

| conference-url = http://www.chi2006.org/

| book-title = Proceedings of the 2006 CHI Conference

| series = Lecture Notes in Computer Science

| volume = 3538

| publisher = Springer

| pages = 955–958

| isbn = 1-59593-372-7

| doi = 10.1145/1124772.1124915

| access-date = 2009-12-30

| url-access = subscription

}}

In 2008 GroupLens launched Cyclopath,{{cite web|url=http://cyclopath.org |title=cyclopath.org |publisher=cyclopath.org |access-date=2012-01-06}} a computational geo-wiki for bicyclists within a city.

{{cite news

| url = http://www.startribune.com/lifestyle/25620134.html

| title = Biking website pools cyclists' expertise

| first = Tony

| last = Gonzalez

| newspaper = Star Tribune

| location = Minneapolis

| date = July 18, 2008

| access-date = 2010-01-04

}}

{{cite news

|title=Mapquest for the cycling set

|first=Richard

|last=Chin

|newspaper=St. Paul Pioneer Press

|page=A1

|date=July 19, 2008

|url=http://www.twincities.com/ci_9928054

|url-status=dead

|archive-url=https://web.archive.org/web/20150218165434/http://www.twincities.com/ci_9928054

|archive-date=February 18, 2015

}}

.

In 2010, GroupLens won the annual ACM software system award.{{cite web|url=http://awards.acm.org/software_system/year.cfm|title=Software System Award - Award Winners: List By Year|work=acm.org|access-date=2013-08-24|archive-date=2016-05-05|archive-url=https://web.archive.org/web/20160505152017/http://awards.acm.org/software_system/year.cfm|url-status=dead}} Riedl died in 2013.{{Cite web|title=Obituary: U's John Riedl was pioneer of recommender systems|url=https://www.startribune.com/obituary-u-s-john-riedl-was-pioneer-of-recommender-systems/217247711/|access-date=2021-03-14|website=Star Tribune}}

Brent Hecht joined the GroupLens faculty in 2013, focusing on geographic human-computer interaction. Lana Yarosh joined the GroupLens faculty in 2014; she works with social computing and child-computer interaction. A third professor, Haiyi Zhu, joined in 2015. Haiyi has published research on Facebook and other social networks. Stevie Chancellor, a human-centered computing and social computing researcher, joined the GroupLens faculty in 2020.{{cite web

|title=New professor brings focus on human-centered machine learning

|date=June 5, 2020

| url=https://cse.umn.edu/cs/news/new-professor-brings-focus-human-centered-machine-learning

}}

• The MovieLens recommender system: MovieLens is a non-commercial movie recommender system that has been running since 1997 with over 164,000 unique visitors as of 2009, who have provided over 15 million movie ratings.

{{cite conference

| url = http://www.grouplens.org/node/412

| title = Tagsplanations: Explaining Recommendations using Tags

| first1 = Jesse

| last1 = Vig

| first2 = Shilad

| last2 = Sen

| first3 = John

| last3 = Riedl

| year = 2009

| conference = International Conference on Intelligent User Interfaces

| conference-url = http://iuiconf.org/

| book-title = Proceedings of the 13th international conference on Intelligent user interfaces

| publisher = ACM Press

| pages = 47–56

| isbn = 978-1-60558-168-2

| doi = 10.1145/1502650.1502661

| access-date = 2009-12-30

| url-access = subscription

}}

• MovieLens ratings datasets: In the early days of recommender systems, research was slowed down by the lack of publicly available datasets. In response to requests from other researchers, GroupLens released three datasets:{{Cite web|url=http://www.grouplens.org/node/73|title = MovieLens|date = 6 September 2013}} the MovieLens 100,000 rating dataset, the MovieLens 1 million rating dataset, and the MovieLens 10 million rating dataset. These datasets became the standard datasets for recommender research, and have been used in over 300 papers by researchers around the world. The dataset is also being used for teaching about recommender technology.

{{cite book

| title = Programming Collective Intelligence: Building Smart Web 2.0 Applications

| last = Segaran

| first = Toby

| publisher = O'Reilly Media

| date = August 2007

| isbn = 978-0-596-52932-1

| url = https://archive.org/details/programmingcolle00sega_0

}}

• MovieLens tagging dataset: GroupLens added tagging to MovieLens in 2006. Since then, users have provided over 85,000 applications of 14,000 unique tags to movies.

{{cite conference

| url = http://www.grouplens.org/node/279

| title = Tagommenders: Connecting Users to Items through Tags

| first1 = Shilad

| last1 = Sen

| first2 = Jesse

| last2 = Vig

| first3 = John

| last3 = Riedl

| year = 2009

| conference = International World Wide Web Conference

| conference-url = http://www2009.org/

| book-title = Proceedings of the 18th international conference on World wide web

| publisher = ACM Press

| pages = 671–680

| isbn = 978-1-60558-487-4

| doi = 10.1145/1526709.1526800

| access-date = 2009-12-29

| url-access = subscription

}} The MovieLens 10 million ratings dataset also includes a 100,000 tag applications dataset for researchers to use.

• Information leakage from recommender datasets: a paper in the information retrieval conference analyzed the privacy risks to users of having large recommender datasets released. The basic risk discovered is that an anonymized dataset might be combined with public information to identify a user. For instance, a user who has written about his preference for movies on online forums could be associated with a specific row in the MovieLens datasets. In some cases, these associations might leak information the user would prefer to keep private.

{{cite conference

| url = https://archive.org/details/sigirseattle20060000inte/page/565

| title = You are what you say: privacy risks of public mentions

| first1 = Dan

| last1 = Frankowski

| first2 = Dan

| last2 = Cosley

| first3 = Shilad

| last3 = Sen

| first4 = Loren

| last4 = Terveen

| first5 = John

| last5 = Riedl

| year = 2006

| conference = Annual ACM Conference on Research and Development in Information Retrieval

| conference-url = http://www.sigir.org/

| book-title = Proceedings of the 29th annual international ACM SIGIR conference on Research and development in information retrieval

| publisher = ACM Press

| pages = [https://archive.org/details/sigirseattle20060000inte/page/565 565–572]

| isbn = 1-59593-369-7

| doi = 10.1145/1148170.1148267

| access-date = 2009-12-29

}}

{{cite web

| url = http://www.schneier.com/blog/archives/2006/08/privacy_risks_o_1.html

| title = Schneier on Security: A blog covering security and security technology

| last = Schneier

| first = Bruce

| author-link = Bruce Schneier

|date=August 2006

| access-date = 2009-12-29

}}

• Wikipedia research: The study of value and vandalism in Wikipedia published in 2007{{cite conference

| url = http://www.grouplens.org/node/113

| title = Creating, Destroying, and Restoring Value in Wikipedia

| first1 = Reid

| last1 = Priedhorsky

| first2 = Jilin

| last2 = Chen

| first3 = Shyong (Tony)

| last3 = Lam

| first4 = Katherine

| last4 = Panciera

| first5 = Loren

| last5 = Terveen

| first6 = John

| last6 = Riedl

| year = 2007

| conference = Conference on Supporting Group Work

| conference-url = http://www.acm.org/conferences/group/conferences/group07/

| book-title = Proceedings of the 2007 international ACM conference on Supporting group work

| publisher = ACM Press

| pages = 259–268

| isbn = 978-1-59593-845-9

| doi = 10.1145/1316624.1316663

| access-date = 2009-12-29

| archive-url = https://web.archive.org/web/20101215143322/http://grouplens.org/node/113

| archive-date = 2010-12-15

| url-status = dead

| url-access = subscription

}} described the concentration of contribution across Wikipedia editors. This paper was one of the first to focus on the length of time that a contribution survives within Wikipedia as a measure of its value. The paper also investigated the effects of vandalism on Wikipedia readers, by measuring the probability that a view of a page would capture that page in a vandalized state. GroupLens has also explored ways to help editors find pages which they can effectively contribute to with the SuggestBot recommender.

{{cite conference

| url = http://www.grouplens.org/node/105

| title = SuggestBot: Using Intelligent Task Routing to Help People Find Work in Wikipedia

| first1 = Dan

| last1 = Cosley

| first2 = Dan

| last2 = Frankowski

| first3 = Loren

| last3 = Terveen

| first4 = John

| last4 = Riedl

| year = 2008

| conference = Conference on Intelligent User Interfaces

| book-title = Proceedings of the 12th international conference on Intelligent user interfaces

| publisher = ACM Press

| pages = 32–41

| isbn = 978-1-59593-481-9

| doi = 10.1145/1216295.1216309

| access-date = 2010-01-04

| url-access = subscription

}} The group has also explored the evolution of the norms in Wikipedia that determine which articles are accepted or rejected, and the effect of changes in those norms on the Long Tail of Wikipedia articles.

{{cite conference

| url = http://www.grouplens.org/node/414

| title = Is Wikipedia Growing a Longer Tail?

| first1 = Shyong (Tony) K.

| last1 = Lam

| first2 = John

| last2 = Riedl

| year = 2009

| conference = International Conference on Supporting Group Work

| conference-url = http://www.acm.org/conferences/group/conferences/group09/

| book-title = Proceedings of the 2009 international ACM conference on Supporting Group Work

| publisher = ACM Press

| pages = 105–114

| isbn = 978-1-60558-500-0

| doi = 10.1145/1531674.1531690

| access-date = 2010-01-04

| url-access = subscription

}} GroupLens has also explored the functioning of the informal peer review system within Wikipedia to discover ways the decisions being made appear to be influenced inappropriately by ownership, and that experience does not seem to change editor performance very much.

{{cite conference

| url = http://www.grouplens.org/node/416

| title = A Jury of Your Peers: Quality, Experience and Ownership in Wikipedia

| first1 = Aaron

| last1 = Halfaker

| author-link1= Aaron Halfaker

| first2 = Aniket

| last2 = Kittur

| first3 = Robert

| last3 = Kraut

| first4 = John

| last4 = Riedl

| year = 2009

| conference = International Symposium on Wikis and Open Collaboration

| conference-url = http://www.wikisym.org/ws2009/

| book-title = Proceedings of the 2009 International Symposium on Wikis and Open Collaboration

| publisher = ACM Press

| isbn = 978-1-60558-730-1

| doi = 10.1145/1641309.1641332

| access-date = 2010-01-04

| url-access = subscription

}}

{{cite conference

| url = http://www.grouplens.org/node/416

| title = Wikipedians are born, not made: a study of power editors on Wikipedia

| first1 = Katherine

| last1 = Panciera

| first2 = Aaron

| last2 = Halfaker

| first3 = Loren

| last3 = Terveen

| year = 2009

| conference = International Conference on Supporting Group Work

| conference-url = http://www.acm.org/conferences/group/conferences/group09/

| book-title = Proceedings of the 2009 international ACM conference on Supporting Group Work

| publisher = ACM Press

| isbn = 978-1-60558-500-0

| doi = 10.1145/1531674.1531682

| access-date = 2010-01-04

| url-access = subscription

}}

GroupLens researchers have also explored visualizations of the edit history of Wikipedia articles.

{{cite conference

| url = http://www.grouplens.org/node/427

| title = rv you're dumb: Identifying Discarded Work in Wiki Article History

| first1 = Michael

| last1 = Ekstrand

| first2 = John

| last2 = Riedl

| year = 2009

| conference = International Symposium on Wikis and Open Collaboration

| conference-url = http://www.wikisym.org/ws2009/

| book-title = Proceedings of the 2009 International Symposium on Wikis and Open Collaboration

| publisher = ACM Press

| isbn = 978-1-60558-730-1

| doi = 10.1145/1641309.1641317

| access-date = 2010-01-04

| url-access = subscription

}} In 2011, the GroupLens researchers completed a scientific exploration of gender imbalance in Wikipedia's popular editors, resulting in finding that there was a large gap between male and female editors.{{cite conference

| url = http://www.grouplens.org/node/466

| title = WP: Clubhouse? An Exploration of Wikipedia's Gender Imbalance

| first1 = Shyong K.

| last1 = Lam

| first2 = Uduwage

| last2 = Anuradha

| first3 = Dong

| last3 = Zhenhua

| first4 = Shilad

| last4 = Sen

| first5 = John

| last5 = Riedl

| year = 2011

| conference = The International Symposium on Wikis and Open Collaboration

| conference-url = http://www.wikisym.org/ws2011/start

| book-title = Proceedings of the 7th international symposium on wikis and open collaboration

| publisher = ACM Press

| pages = 1–10

| doi = 10.1145/2038558.2038560

| access-date = 2011-10-25

| archive-date = 2011-09-20

| archive-url = https://web.archive.org/web/20110920031047/http://www.grouplens.org/node/466

| url-status = dead

| url-access = subscription

}}

• Shilling recommender systems: GroupLens has explored ways that users of recommender systems can attempt to inappropriately influence the recommendations given to other users.

{{cite conference

| url = http://www.grouplens.org/node/148

| title = Shilling recommender systems for fun and profit

| first1 = Shyong K.

| last1 = Lam

| first2 = John

| last2 = Riedl

| year = 2004

| conference = International World Wide Web Conference

| conference-url = http://www.iw3c2.org/WWW2004/

| book-title = Proceedings of the 13th international conference on World Wide Web

| publisher = ACM Press

| pages = 393–402

| isbn = 1-58113-844-X

| doi = 10.1145/988672.988726

| access-date = 2010-01-04

| url-access = subscription

}} They call this behavior shilling, because of its relationship to the practice of hiring associates to pretend to be enthusiastic customers. They showed that some types of shilling are likely to be effective in practice. One concern about shilling is that the false predictions may change the reported opinions of later users, further corrupting the recommendations.

{{cite news

| url = https://www.nytimes.com/2003/05/22/technology/false-web-ratings-swing-opinion-study-says.html

| title = False Web Ratings Swing Opinion, Study Says

| first = Julie

| last = Charles

| date = May 22, 2003

| newspaper = The New York Times

| page = G4

| access-date = 2009-12-23

}}

{{cite conference

| url = http://www.grouplens.org/node/158

| title = Is Seeing Believing? How Recommender Systems Influence Users' Opinions

| first1 = Dan

| last1 = Cosley

| first2 = Shyong K.

| last2 = Lam

| first3 = Istvan

| last3 = Albert

| first4 = Joseph A.

| last4 = Konstan

| first5 = John

| last5 = Riedl

| year = 2003

| conference = Conference on Human Factors in Computing Systems

| conference-url = http://www.chi2003.org/

| book-title = ACM SIGCHI Conference on Human Factors in Computing Systems

| publisher = ACM Press

| isbn = 1-58113-630-7

| doi = 10.1145/642611.642713

| access-date = 2010-01-04

| url-access = subscription

}}

• Cyclopath: Beginning in 2008, GroupLens launched Cyclopath, a computational geo-wiki for local bicyclists. Cyclopath has since been used by hundreds of cyclists within the Twin Cities.{{cite conference

| url = http://www.grouplens.org/node/434

| title = Eliciting and Focusing Geographic Volunteer Work

| first1 = Reid

| last1 = Priedhorsky

| first2 = Mikhil

| last2 = Masli

| first3 = Loren

| last3 = Terveen

| year = 2010

| conference = Conference on Computer Supported Cooperative Work

| conference-url = http://www.cscw2010.org/

| book-title = Proceedings of the 2010 ACM conference on Computer supported cooperative work

| publisher = ACM Press

| isbn = 978-1-60558-795-0

| doi = 10.1145/1718918.1718931

| access-date = 2010-03-02

| archive-url = https://web.archive.org/web/20100612222015/http://grouplens.org/node/434

| archive-date = 2010-06-12

| url-status = dead

}} More recently, Cyclopath has been adopted by the Twin Cities Metropolitan Council to help plan the regional cycling system.

{{reflist|2}}

• [https://www.grouplens.org/ GroupLens Research Homepage]

{{University of Minnesota campus}}

Category:University of Minnesota

Category:Human–computer interaction

Category:Computer science research organizations

Category:Research organizations in the United States

Category:Recommender systems