WhoContributestotheKnowledgeSharingEconomy?ArthiRamachandran,Augus1nChaintreau

ColumbiaUniversityNov2,2015

KnowledgeSharingEconomy

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Whobringsmorepeopletowebsites?

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KnowledgeSharingEconomy

•  Socialisincreasingintheshareofreferrals

KnowledgeSharingEconomy

•  Similartothesharingeconomy(eg:uber,airbnb),whereusersbenefitfromotherusers’surplus

KnowledgeSharingEconomy

•  Similartothesharingeconomy(eg:uber,airbnb),whereusersbenefitfromotherusers’surplus

•  IntheKnowledgeSharingEconomy,otherusersbenefitfromusers’informa1onsearch

KnowledgeSharingEconomy

•  Informa1onis–  Financiallyimportant

•  Infact,intermediariescanearnalivingbycura1ngcontent1,2

–  Usedfordecisionmaking3,4•  Eg:jobhun1ng,vo1ng,newproducts

1M.Cha,F.Benevenuto,H.Haddadi,andK.Gummadi.TheWorldofConnec1onsandInforma1onFlowinTwiXer.Systems,ManandCyberne1cs,PartA:SystemsandHumans,IEEETransac1onson,2012.2S.Wu,J.M.Hofman,W.A.Mason,andD.J.WaXs.WhosayswhattowhomontwiXer.WWW2011.3D.Acemoglu,A.Ozdaglar,andA.ParandehGheibi.Spreadof(mis)informa1oninsocialnetworks.GamesandEconomicBehavior,2010.4B.GolubandM.O.Jackson.Naivelearninginsocialnetworksandthewisdomofcrowds.AmericanEconomicJournal:Microeconomics,2010.

KnowledgeSharingEconomy

•  Informa1onis–  Financiallyimportant

•  Infact,intermediariescanearnalivingbycura1ngcontent1,2

–  Usedfordecisionmaking3,4•  Eg:jobhun1ng

•  Theseanalyzeinforma1onacquisi1onasaneconomicra1onalprocess

1M.Cha,F.Benevenuto,H.Haddadi,andK.Gummadi.TheWorldofConnec1onsandInforma1onFlowinTwiXer.Systems,ManandCyberne1cs,PartA:SystemsandHumans,IEEETransac1onson,2012.2S.Wu,J.M.Hofman,W.A.Mason,andD.J.WaXs.WhosayswhattowhomontwiXer.WWW2011.3D.Acemoglu,A.Ozdaglar,andA.ParandehGheibi.Spreadof(mis)informa1oninsocialnetworks.GamesandEconomicBehavior,2010.4B.GolubandM.O.Jackson.Naivelearninginsocialnetworksandthewisdomofcrowds.AmericanEconomicJournal:Microeconomics,2010.

Modelsofcontentsharing

•  Past:publisher->readermodel

Modelsofcontentsharing

•  Withsocialnetworks:publisher->curators->readermodel

Modelsofcontentsharing

•  Withsocialnetworks:publisher->curators->readermodel

?

Typesofsharing

•  Whereisthecontentcomingfrom?WholooksforcontenttoshareontwiXer?

Typesofsharing

•  Whereisthecontentcomingfrom?WholooksforcontenttoshareontwiXer?

•  Heterogeneoussharing– Contentthatmanyusersfindandshare

Typesofsharing

•  Whereisthecontentcomingfrom?WholooksforcontenttoshareontwiXer?

•  Heterogeneoussharing– Contentthatmanyusersfindandshare– Contentthatismorespecialized

Outline

•  Datasets•  WhoaretheContentCreators?•  Rela1onshipofContentLifespanandConcentra1on

•  ModelofPerishablePublicGoods•  EquilibriaandSpecializa1on•  Conclusion

Outline

•  Datasets•  WhoaretheContentCreators?•  Rela1onshipofContentLifespanandConcentra1on

•  ModelofPerishablePublicGoods•  EquilibriaandSpecializa1on•  Conclusion

Datasets

•  KAIST:TwiXerpostsoverJuly2009– Breadth–alltwiXerusersandpostsforamonth– 8muniqueusers– 37muniqueURLs

•  NYT:TwiXerpostscontainingURLstony1mes.comfor1weekinDec2012– Depth–alltwiXerusersreceivingcertainurls– 346kuniqueusers– 70kuniqueURLs

M.Cha,H.Haddadi,F.Benevenuto,andK.Gummadi.MeasuringUserInfluenceinTwiXer:TheMillionFollowerFallacy.ICWSM2010.May,A.Chaintreau,N.Korula,andS.LaXanzi.Filter&Follow:HowSocialMediaFosterContentCura1on.SIGMETRICS2014

Outline

•  Datasets•  WhoaretheContentCreators?•  Rela1onshipofContentLifespanandConcentra1on

•  ModelofPerishablePublicGoods•  EquilibriaandSpecializa1on•  Conclusion

WhoisResponsibleforCreatingContent?

SocialNetwork

•  Networkofusers

WhoisResponsibleforCreatingContent?

SocialNetwork

•  Networkofuserspos1ng()content

WhoisResponsibleforCreatingContent?

SocialNetwork

•  Differentclassesofuserposts:– Anyonewhoposts

WhoisResponsibleforCreatingContent?

SocialNetwork

•  Differentclassesofuserposts:– Anyonewhoposts– Locallythefirsttopost

WhoisResponsibleforCreatingContent?

SocialNetwork

•  Differentclassesofuserposts:– Anyonewhoposts–  Locallythefirsttopost– Globallythefirsttopost(veryoriginalcontent)

WhoisResponsibleforCreatingContent?

•  Howmanyusersareresponsibleforhowmanyposts?

WhoisResponsibleforCreatingContent?

•  Howmanyusersareresponsibleforhowmanyposts?

WhoisResponsibleforCreatingContent?

•  Howmanyusersareresponsibleforhowmanyposts?

WhoisResponsibleforCreatingContent?

WhoisResponsibleforCreatingContent?

=50%ofusersareresponsiblefor

=80%ofposts

WhoisResponsibleforCreatingContent?

Singledomain(cnn.com)

WhoisResponsibleforCreatingContent?

Smallerfrac1onofusersresponsibleforfirsttweets:Moreoriginalcontentismoreconcentrated

•  Comparedifferenttypesofdomains– ny1mes.com

•  Daily,Shorterlifespan

–  theatlan1c.com•  Monthly,Longerlifespan

Butwhathappenstootherdomains?

Butwhathappenstootherdomains?

Butwhathappenstootherdomains?

Shorterlifespanislessconcentrated

Butwhathappenstootherdomains?

ShorterlifespanislessconcentratedLongerlifespanismoreconcentrated

Outline

•  Datasets•  WhoaretheContentCreators?•  Rela1onshipofContentLifespanandConcentra1on

•  ModelofPerishablePublicGoods•  EquilibriaandSpecializa1on•  Conclusion

What’stherelationshipbetweenlifespanandconcentration?

•  Measureoflifespan:Shelflife– ExpectedaXen1onforanar1clebeforeitisreplaced

– Mul1plewaystomeasure•  basedonvolumeoftweets•  basedondura1on

What’stherelationshipbetweenlifespanandconcentration?

•  Measureoflifespan:Shelflife– ExpectedaXen1onforanar1clebeforeitisreplaced

– Mul1plewaystomeasure•  basedonvolumeoftweets•  basedondura1on

– Hereweusetheonebasedonvolume

Concentrationofsharingfordifferentmediasources

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1mn 10mn 60mn 180mn0.01%

0.05%0.10%

0.50%1.00%

theatl

antic.

com

theon

ion.co

m

slate.

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online

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newyo

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om

usne

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reuter

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washin

gtonp

ost.c

om

wired.c

om

time.c

om

cnn.c

om

mirror.c

o.uk

vanit

yfair.c

om

usato

day.c

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bbc.c

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omist.

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ion.co

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Time between unique content (minutes)

90%−v

olum

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igin

ator

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ale)

type● All_posts

Global_firstLocal_first

Frac1o

nofusersre

spon

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0%ofthe

con

tent

ShelfTime(minutes)

Observations

•  Specializa1onexists

Observations

•  Specializa1onexists•  Understandingwhocontributesisnottrivial

•  Eg:Originalcontentdoesn’tcomefromthehighestdegreenodes

Observations

•  Specializa1onexists•  Understandingwhocontributesisnottrivial

•  Eg:Originalcontentdoesn’tcomefromthehighestdegreenodes

•  Timeinanimportantfactor•  Shortlivedcontentreducesspecializa1on

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●

1mn 10mn 60mn 180mn0.01%

0.05%0.10%

0.50%1.00%

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antic.

com

theon

ion.co

m

slate.

com

online

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wired.c

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cnn.c

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mirror.c

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vanit

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omist.

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theatl

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theon

ion.co

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slate.

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online

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busin

essw

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washin

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ion.co

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huffin

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wired.c

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time.c

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cnn.c

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mirror.c

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npr.o

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omist.

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ft.com

Time between unique content (minutes)

90%−v

olum

e or

igin

ator

s(lo

g−sc

ale)

type● All_posts

Global_firstLocal_first

Observations•  Specializa1onexists•  Understandingwhocontributesisnottrivial

•  Eg:Originalcontentdoesn’tcomefromthehighestdegreenodes

•  Timeinanimportantfactor•  Shortlivedcontentreducesspecializa1on

•  Whatarethecondi1onsunderwhichspecializa1onoccurs?–  Formally?– Whatdynamicscausesthiseffect?

Outline

•  Datasets•  WhoaretheContentCreators?•  Rela1onshipofContentLifespanandConcentra1on

•  ModelofPerishablePublicGoods•  EquilibriaandSpecializa1on•  Conclusion

PerishablePublicGoodsModel

•  Proper1esofthemodel– Specializa1onexists– Understandingwhocontributesisnottrivial

•  Eg:Originalcontentdoesn’tcomefromthehighestdegreenodes

– Timeinanimportantfactor•  Shortlivedcontentreducesspecializa1on

FindingInformation

FindingInformation

FindingInformation

Cost

FindingInformation

Cost

FindingInformation

ny1mes.com/2015/…

Cost

FindingInformation

ny1mes.com/2015/…

Value

Cost

ChoosingInvestmenttoFindInformation

ny1mes.com/2015/…

Value

Cost

�

> 0 =)

ChoosingInvestmenttoFindInformation

ny1mes.com/2015/…

Value

Cost

� Spendsefforttofindcontent

> 0 =)

ChoosingInvestmenttoFindInformation

ny1mes.com/2015/…

Value

Cost

�

< 0 =)�

Spendsefforttofindcontent

DoesNOTspendefforttofindcontent

PublicGoodsModel

PerishablePublicGoodsModel

PerishablePublicGoodsModel

ny1mes.com/2015/…

PerishablePublicGoodsModel

ny1mes.com/2015/…

PerishablePublicGoodsModel

PerishablePublicGoodsModel

Value

PerishablePublicGoodsModel

ValueCost

PerishablePublicGoodsModel

ValueCost

PerishablePublicGoodsModel

ValueCost

PerishablePublicGoodsModel

ValueCost

PerishablePublicGoodsModel

ValueCost

PerishablePublicGoodsModel

ValueCost

U(yi, y�i) = f(

PerishablePublicGoodsModel

ValueCost

yi =

y�i =

)� c( )

PublicGoodsModel

ValueCost

y�i =

U(yi, y�i) = f( )� c( )

yi =

PublicGoodsModel

ValueCost

Assume:•  anar1clehasashelflifeofτ•  yiistherateofdiscoveryofinforma1on

U(yi, y�i) = f( )� c( )

PerishablePublicGoodsModel

ValueCost

Assume:•  anar1clehasashelflifeofτ•  yiistherateofdiscoveryofinforma1on

U(yi, y�i) = (1� e⌧(yi+y�i))� c(yi)

U(yi, y�i) = f( )� c( )

Strategiesforauser

ValueCost ValueCost

Free-riding Equitabledistribu1on

Outline

•  Datasets•  WhoaretheContentCreators?•  Rela1onshipofContentLifespanandConcentra1on

•  ModelofPerishablePublicGoods•  EquilibriaandSpecializa1on•  Conclusion

TypesofEquilibria

•  Equitabledistribu1onofwork

TypesofEquilibria

•  Specializeddistribu1onofwork

THM:ConditionsforSpecialization⌧ < ⌧̂ = f(�min)

yes no?

Smallerlessspecializedequilibriumi.e.shorterlivedcontentislessspecialized

⌧ =) Specializa1onoccurswithlongerlivedcontent

Specialization:ToyExample

•  Howmucheffortdoeseachpersonexpend?

Specialization:ToyExampleDependson⌧

Specialization:ToyExampleDependson

Longershelflife

Effortd

onebyanod

e

⌧

Specialization:ToyExample

Longershelflife

Effortd

onebyanod

e

Specialization:ToyExample

Longershelflife

Effortd

onebyanod

e

Specialization:ToyExample

Longershelflife

Effortd

onebyanod

e

SpecializationinDifferentGraphs

Graph

Complete -1

Cycle(Even) -2

Cycle(Odd)

Erdös-Renyi

Star

CompleteBipar1te

Conclusion

•  Specializa1onoccursinsocialgraphs– Longlivedcontentexhibitsspecializa1on– Specializa1oncannotoccurforarbitrarilyshortlivedcontent

•  Theexistenceofspecializedequilbriaarebasedonproper1esofthegraph

Thankyou

AnyQues1ons?

BestResponse

ConditionforNashEquilibrium