No Slide TitleDr. Bhavani Thuraisingham
http://www.flairandsquare.com/archives/167
A social network site allows people who share interests to build a
‘trusted’ network/ online community. A social network site will
usually provide various ways for users to interact, such as IM
(chat/ instant messaging), email, video sharing, file sharing,
blogging, discussion groups, etc.
The main types of social networking sites have a ‘theme’, they
allow users to connect through image or video collections online
(like Flicker or You Tube) or music (like My Space, lastfm). Most
contain libraries/ directories of some categories, such as former
classmates, old work colleagues, and so on (like Face book, friends
reunited, Linked in, etc). They provide a means to connect with
friends (by allowing users to create a detailed profile page), and
recommender systems linked to trust.
1-*
Popular Social Networks
Face book - A social networking website. Initially the membership
was restricted to students of Harvard University. It was originally
based on what first-year students were given called the “face book”
which was a way to get to know other students on campus. As of July
2007, there over 34 million active members worldwide. From
September 2006 to September 2007 it increased its ranking from 60
to 6th most visited web site, and was the number one site for
photos in the United States.
Twitter- A free social networking and micro-blogging service that
allows users to send “updates” (text-based posts, up to 140
characters long) via SMS, instant messaging, email, to the Twitter
website, or an application/ widget within a space of your choice,
like MySpace, Facebook, a blog, an RSS Aggregator/reader.
My Space - A popular social networking website offering an
interactive, user-submitted network of friends, personal profiles,
blogs, groups, photos, music and videos internationally. According
to AlexaInternet, MySpace is currently the world’s sixth most
popular English-language website and the sixth most popular website
in any language, and the third most popular website in the United
States, though it has topped the chart on various weeks. As of
September 7, 2007, there are over 200 million accounts.
1-*
A structural approach to understanding social interaction.
Networks consist of Actors and the Ties between them.
We represent social networks
are the ties.
show the strength of the tie.
In the simplest networks, an Actor is an individual person.
A tie might be “is acquainted with”. Or it might represent the
amount of email exchanged between persons A and B.
1-*
World political and economic system
Community elite decision-making
Belief systems, Social influence
Markets, Sociology of science
1-*
“Sociograms” were invented in 1933 by Moreno.
In a sociogram, the actors are represented as points in a
two-dimensional space. The location of each actor is significant.
E.g. a “central actor” is plotted in the center, and others are
placed in concentric rings according to “distance” from this
actor.
Actors are joined with lines representing ties, as in a social
network. In other words a social network is a graph, and a
sociogram is a particular 2D embedding of it.
These days, sociograms are rarely used (most examples on the web
are not sociograms at all, but networks). But methods like MDS
(Multi-Dimensional Scaling) can be used to lay out Actors, given a
vector of attributes about them.
Social Networks were studied early by researchers in graph theory
(Harary et al. 1950s). Some social network properties can be
computed directly from the graph.
Others depend on an adjacency matrix representation (Actors index
rows and columns of a matrix, matrix elements represent the tie
strength between them).
1-*
Balance: important in exchange networks
In a two-person network (dyad), exchange of goods, services and
cash should be balanced.
More generally, exchanges of “favors” or “support” are likely to be
quite balanced.
Role: what role does the actor perform in the network?
Role is defined in terms of Actors’ neighborhoods.
The neighborhood is the set of ties and actors connected directly
to the current actor.
Actors with similar or identical neighborhoods are assigned the
same role.
What is the related idea from semiotics?
Paradigm: interchangability. Actors with the same role are
interchangable in the network.
Related notions are status and centrality.
Centrality reifies the notion of “peripheral vs. central
participation” from communities of practice.
Key notions of centrality were developed in the 1970’s, e.g.
“eigenvalue centrality” by Bonacich.
Most of these measures were rediscovered as quality measures for
web pages:
Indegree
Actor
An “actor” is a basic component for SNs. Actors can be:
Individual people, Corporations, Nation-States, Social groups
Modes
If all the actors are of the same type, the network is called a
one-mode network. If there are two groups of actor then it is a
two-mode network.
E.g. an affiliation network is a two-mode network. One mode is
individuals, the other is groups to which they belong. Ties
represent the relation: person A is a member of group B.
Ties
A tie is the relation between two actors. Common types of ties
include:
Friendship, Amount of communication, Goods exchanged, Familial
relation (kinship), Institutional relations
1-*
Because human relations are rich and unbounded, drawing meaningful
boundaries for network analysis is a challenge.
There are two main approaches:
Realist: boundaries perceived by actors themselves, e.g. gang
members or ACM members.
Nominalist: Boundaries created by researcher: e.g. people who
publish in ACM CHI.
To deal with large networks, sampling is necessary. Unfortunately,
randomly sampled graphs will typically have completely different
structure. Why?
One approach to this is “snowballing”. You start with a random
sample. Then extend with all actors connected by a tie. Then extend
with all actors connected to the previous set by a tie…
1-*
Social Network Analysis of 9/11 Terrorists (www.orgnet.com)
Early in 2000, the CIA was informed of two terrorist suspects
linked to al-Qaeda.
Nawaf Alhazmi and Khalid Almihdhar were photographed attending a
meeting of
known terrorists in Malaysia. After the meeting they returned to
Los Angeles,
where they had
1-*
Social Network Analysis of 9/11 Terrorists
What do you do with these suspects? Arrest or deport them
immediately? No, we need to use them to discover more of the
al-Qaeda network.
Once suspects have been discovered, we can use their daily
activities to uncloak their network. Just like they used our
technology against us, we can use their planning process against
them. Watch them, and listen to their conversations to see...
who they call / email
where their money comes from
The structure of their extended network begins to emerge as data is
discovered via surveillance.
1-*
Social Network Analysis of 9/11 Terrorists
A suspect being monitored may have many contacts -- both accidental
and intentional. We must always be wary of 'guilt by association'.
Accidental contacts, like the mail delivery person, the grocery
store clerk, and neighbor may not be viewed with investigative
interest.
Intentional contacts are like the late afternoon visitor, whose car
license plate is traced back to a rental company at the airport,
where we discover he arrived from Toronto (got to notify the
Canadians) and his name matches a cell phone number (with a
Buffalo, NY area code) that our suspect calls regularly. This
intentional contact is added to our map and we start tracking his
interactions -- where do they lead? As data comes in, a picture of
the terrorist organization slowly comes into focus.
How do investigators know whether they are on to something big?
Often they don't. Yet in this case there was another strong clue
that Alhazmi and Almihdhar were up to no good -- the attack on the
USS Cole in October of 2000. One of the chief suspects in the Cole
bombing [Khallad] was also present [along with Alhazmi and
Almihdhar] at the terrorist meeting in Malaysia in January
2000.
Once we have their direct links, the next step is to find their
indirect ties -- the 'connections of their connections'.
Discovering the nodes and links within two steps of the suspects
usually starts to reveal much about their network. Key individuals
in the local network begin to stand out. In viewing the network map
in Figure 2, most of us will focus on Mohammed Atta because we now
know his history. The investigator uncloaking this network would
not be aware of Atta's eventual importance. At this point he is
just another node to be investigated.
1-*
Figure 2 shows the two suspects and
1-*
Figure 2 shows the two suspects and
1-*
We now have enough data for two key conclusions:
All 19 hijackers were within 2 steps of the two original suspects
uncovered in 2000!
Social network metrics reveal Mohammed Atta emerging as the local
leader
With hindsight, we have now mapped enough of the 9-11 conspiracy to
stop it. Again, the investigators are never sure they have
uncovered enough information while they are in the process of
uncloaking the covert organization. They also have to contend with
superfluous data. This data was gathered after the event, so the
investigators knew exactly what to look for. Before an event it is
not so easy.
As the network structure emerges, a key dynamic that needs to be
closely monitored is the activity within the network. Network
activity spikes when a planned event approaches. Is there an
increase of flow across known links? Are new links rapidly emerging
between known nodes? Are money flows suddenly going in the opposite
direction? When activity reaches a certain pattern and threshold,
it is time to stop monitoring the network, and time to start
removing nodes.
The author argues that this bottom-up approach of uncloaking a
network is more effective than a top down search for the terrorist
needle in the public haystack -- and it is less invasive of the
general population, resulting in far fewer "false positives".
1-*
Figure 2 shows the two suspects and
When the Mitchell Report on steroid use in Major League Baseball
[MLB], was published, people were surprised at who and how many
players were mentioned. The diagram below shows a human network
created from data found in the Mitchell Report. Baseball players
are shown as green nodes. Those who were found to be providers of
steroids and other illegal performance enhancing substances appear
as red nodes. The links reveal the flow of chemicals -- from
provider to player.
1-*
Networks of Adaptive/Agile Organizations
Discovering Communities of Practice
Post-Merger Integration
Decision-Making in Organizations
New Organizational Structures
Figure 2 shows the two suspects and
1-*
Figure 2 shows the two suspects and
Organizational leaders are preparing for the potential loss of
expertise and knowledge flow due to turnover, downsizing,
outsourcing, and the coming retirements of the baby boom
generation. The model network (previous chart) is used to
illustrate the knowledge continuity analysis process.
Each node in this sample network (previous chart) represents a
person that works in a knowledge domain. Some people have more /
different knowledge than others. Employees who will retire in 2
years or less have their nodes colored red. Those who will retire
in 3-4 years are colored yellow. Those retiring in 5 years or later
are colored green.
A gray, directed line is drawn from the seeker of knowledge to the
source of expertise. A-->B indicates that A seeks expertise /
advice from B. Those with many arrows pointing to them are sought
often for assistance.
The top subject matter experts -- SMEs -- in this group are nodes
29, 46, 100, 41, 36 and 55.
The SMEs were discovered using a network metric in InFlow that is
similar to how the
Google search engine ranks web pages -- using both direct and
indirect links.
Of the top six SMEs in this group, half are colored red[100] or
yellow[46, 55]. The loss of person 46 has the greatest potential
for knowledge loss. 90% of the network is within
3 steps of accessing this key knowledge source.
1-*
Social Networks: Security and Privacy Issues: European Network and
Information Security Agency
The European Network and Information Security Agency (ENISA) has
released its first issue paper “Security Issues and Recomendations
for Online Social Networks".
http://www.enisa.europa.eu/doc/pdf/deliverables/enisa_pp_social_networks.pdf
Four groups of threats: privacy related threats, variants of
traditional network and information security threats, identity
related threats, social threats.
Recommendations are given for governments (oversight and adaption
of existing data protection legislation), companies that run such
networks, technology developers, and research and standardisation
bodies.
Some concenrs: recommnendation to use automated filters against
"offensive, litigious or illegal content". This brings potential
freedom of speech issues. European Digital Rights has started a
campaign against a similar recommendation by the Council of
Europe.
Issue of portability of profiles social graphs are also addressed.
However what is missing is that “Information about social links is
not about only one user, but also the others which he is linked to.
They have to agree if this information is moved to different
platforms”.
1-*
Social Networks: Security and Privacy Issues: Microsoft
Recommendations
http://www.microsoft.com/protect/yourself/personal/communities.mspx
Online communities require you to provide personal information.
Profiles are public. Comments you post are permanently recorded on
the community site.You might even mention when you plan to be out
of town.
E-mail and phishing scammers count on the appealing sense of trust
that is often fostered in online communities to steal your personal
information. The more you reveal in profiles and posts, the more
vulnerable you are to scams, spam, and identity theft.
Here are some features to look for when you're considering joining
an online community: