a sample of basic Cs system types on the World-Wide Web.

nature of
Collaboration architecture
must
recruit
users? What users do?

examples target Problems Comments

˲˲ reviewing and voting at Amazon,
tagging Web pages at del.ici.ous.com
and Google Co-op
Evaluating a
collection of items
(e.g., products, users)

humans as perspective providers. no or loose combination of inputs.

Sharing

˲˲ items

˲˲ textual knowledge

˲˲ structured knowledge

˲˲ napster, You Tube, Flickr, CPAn, programmableweb.com

˲˲ Mailing lists, Yahoo! Answers, QuIQ, ehow.com, Quora

˲˲ Swivel, Many Eyes, Google Fusion
Tables, Google Base, bmrb.wisc.edu,
galaxyzoo, Piazza, Orchestra
Building a (distributed
or central) collection
of items that can be
shared among users.

humans as content providers. no or loose combination of inputs.

networking ˲˲ LinkedIn, MySpace, Facebook
Building social
networks

explicit

Standalone
Yes
humans as component
providers. Loose
combination of inputs.
humans can play all
roles. Typically tight
combination of inputs.
Some systems ask both
humans and machines
to contribute.

Standalone
Yes
humans can play
all roles. Input
combination can be
loose or tight.

implicit

˲˲ play games with a purpose

˲˲ bet on prediction markets

˲˲ use private accounts ˲˲ solve captchas

˲˲ buy/sell/auction, play
massive multiplayer
games
Piggyback on
another system
no
Building artifacts

˲˲ keyword search
˲˲ buy products
˲˲ browse Web sites

˲˲ Google, Microsoft, Yahoo

˲˲ recommendation feature of Amazon
˲˲ adaptive Web sites
(e.g., Yahoo! front page)

 

How to recruit and retain users? What contributions can users make? How to combine user contributions to solve the target problem? How to evaluate users and their contributions?

Not all human-centric systems ad-
dress these challenges. Consider a
system that manages car traffic in
Madison, WI. Its goal is to, say, coor-
dinate the behaviors of a crowd of hu-
man drivers (that already exist within
the system) in order to minimize traf-
fic jams. Clearly, this system does not
want to recruit more human drivers (in
fact, it wants far fewer of them). We call
such systems crowd management (CM)
systems. CM techniques (a.k.a., “crowd
coordination” 31) can be relevant to CS
contexts. But the two system classes
are clearly distinct.

Classifying CS systems. CS systems can be classified along many dimensions. Here, we discuss nine dimensions we consider most important. The two that immediately come to mind are the nature of collaboration and type of target problem. As discussed previously, collaboration can be explicit or implicit, and the target problem can be any problem defined by the system owners (for example, building temporary or permanent artifacts, executing tasks).

The next four dimensions refer respectively to how a CS system solves the four fundamental challenges described earlier: how to recruit and retain users; what can users do; how to combine