Category Archives: social networks
14 Comments Posted by Bernhard on September 8th 2012 @ 12:36 pm
I am sick this weekend and that’s a justification to stay in bed and play around with the computer a bit. Over these last weeks, I was thinking that it may be interesting to get back to the aging netvizz application and make some direly needed revisions and updates, especially concerning some of the quantitative measures concerning individual users’ activity. Maintenance work is not fun, however, so I decided to add a new feature instead: the bipartite like network.
The idea is pretty simple: instead of graphing friend relationships between users, the new output basically just throws users and likes (liked pages that is – external objects are not available through the API) into the same graph. If a user likes something a link is created. That’s also how Facebook’s opengraph architecture works on the inside. The result – done with gephi – is pretty interesting though (click for bigger image):
The small turquoise dots are users and the bigger red ones liked objects. I eliminated users that did not like anything (or have strong privacy settings), as well as all things liked by a single person only. The data field “likesize” in the output file indicates how often an object has been liked and makes it possible to size likes separately from users (the “type” field distinguishes the two). It is not surprising that, at least in my case, the network of friendship connections and the like network are quite similar. People from Austria do not like the same things as my French friends – although there is a cluster of international stuff in the middle: television shows, music, wikileaks, and so on; these things cannot be clearly attributed to a user group.
One can actually use the same output file for something quite different. The next image shows the same graph but with nodes sized for number of connections (degree). This basically shows the biggest “likers” (anonymized for the purpose of this post) in the network and still keeps the grouped by similar like patterns.
The new feature is already live and can be tried out. If you want to do more than make pretty pictures, I highly recommend checking out the work by my colleagues Carolin Gerlitz and Anne Helmond on what they call the “like economy”.
And now back to bed.
I am currently writing a paper to submit to the new and very exciting journal computational culture on the use of graph theory to produce “evaluative metrics” in contexts like Web search or social networking. One of my core arguments is going to be that the network as descriptive (mathematical) model has never stood in opposition to the notion of hierarchy but should rather be seen as a conceptual tool that was used in different fields (e.g. sociometry, psychometry, citation analysis, etc.) over the 20th century to investigate structure and, in particular, to both investigate and establish hierarchy. This finally gave me an excuse to dive into Jacob L. Moreno’s opus magnum Who Shall Survive? from 1934, which not only founded sociometry but also laid the ground work for social network analysis. This is one of the strangest books I have ever read, not only because the edition from 1978 reveals the author as a deeply Nietzschean character (“Actually, I have written two bibles, an old testament and a new testament.“), but also because the sociogenic therapy Moreno proposes as an approach to the “German-Jewish conflict” puts the whole text in a deeply saddening light. But these aspects only deepen the impression that this is a fascinating book, really one of its kind.
Interestingly, Moreno also discovered what we would now call “power-law dynamics in social networks”. One of the applications of his “sociometric test” – basically a “who do you like” type of questionnaire – in a small American town named Hudson came to the following result:
After the first phase of the sociometric test was given the analysis of the choices revealed that among a population of 435 persons,23 204, or 46.5%, remained unchosen after the 1st choice; 139, or 30%, after the 2d choice; 87, or 20%, after the 3rd choice; 74, or 17%, after the 4th choice; and 66, or 15%, after the 5th choice. (Moreno 1934, p. 249)
This means that 15% of the population was not mentioned when the interviewees were asked which five people in the community they liked best. While this does not make for a particularly skewed distribution, Moreno transposes the result on the population of New York city and adds a quite tantalizing interpretation:
There is no question but that this phenomenon repeats itself throughout the nation, however widely the number of unchosen may vary from 1st to 5th or more choices due to the incalculable influence of sexual, racial, and other psychological currents. For New York, with a population of 7,000,000, the above percentages would be after the 1st choice, 3,200,000 individuals unchosen; after the 2nd choice, 2,100,000 unchosen; after the 3rd choice, 1,400,000 unchosen; after the 4th choice, 1,200,000 unchosen; and after the 5th choice, 1,050,000 unchosen. These calculations suggest that mankind is divided not only into races and nations, religions and states, but into socionomic divisions. There is produced a socionomic hierarchy due to the differences in attraction of particular individuals and groups for other particular individuals and groups. (Moreno 1934, p. 250f)
By looking into the history of the field, I hope to show that the observation of uneven distributions of connectivity in real-world networks, e.g. the work by Hindman and others concerning the Web, are certainly not a discovery of the “new science of networks” of recent years but a virtual constant in mathematical approaches to networks: whenever somebody starts counting, the result is an ordered list, normally with a considerable difference in value between the first and the last element. When it comes to applications of sociometry to sociology or anthropology, the question of leadership, status, influence, etc. is permanently in the forefront, especially from the 1950s onward when matrix algebra starts to allow for quick calculations of different forms of centrality. Contrary to popular myth, when Page and Brin came up with PageRank, they had a very wide variety of inspirational sources to draw from. Networks and ranking had been an old couple for quite a while already.
2 Comments Posted by Bernhard on September 3rd 2011 @ 8:46 am
German publisher Heise Verlag is an international curiosity. It publishes a small number of highly influential computer-related magazines that give a voice to a tech ethos that is at the same time extremely competent in the subject matter (I’ve been a steady subscriber to c’t magazin for over 15 years now, and I am still baffled sometimes just how good it is) and very much aware of the social and political implications of computing (their online magazine Telepolis testifies to that).
Data protection and privacy are long-standing concerns of the heise editors and true to a spirit of society-oriented design, they have introduced a concept as well as a technical implementation of a two-step “like” button. Such buttons, by Facebook or other companies, have of course become a major vector of user-tracking on the Web. By using an iframe, every button loads some code from Facebook’s server and sends the referring url (e.g. http://nytimes.com/articlename/blabla) as an information. The iframe being hosted on the facebook.com domain, cross-site privacy protections can be circumvented, the url information connected to an identifier cookie and, consequently, to a user account. Plugins like the Priv3 project block these mechanisms but a) users have to have a heightened level of awareness to even consider installing something like this and b) the plugin interferes with convenient functions like Google search preferences.
Heise’s suggestion, which they already implemented on their own sites, is simple: websites can download a small bit of code that implements a two-step procedure: the “like” button is greyed out after the page first loads and there is no tracking happening. A first click on the button loads the “real” Facebook code, and the second click provides the usual functionality. The solution is very simple to implement and really a very minor inconvenience. Independently from the debate whether “like” buttons and such add any real value to the Web, this example shows that “social” features like these can be designed in a way that does not necessarily lead to pervasive user tracking.
The echo to this initiative has been very strong (check the Slashdot discussion here), especially in Germany, where privacy (or rather Datenschutz, a concept less centered on the individual but rather on the role of data in society) is an intensely debated issue, due to obvious historical reasons. Facebook apparently threatened to blacklist heise.de at a point, but has since then backpedaled. After all, c’t magazin prints around 600.000 issues of every number and is extremely influential in the German (and Dutch!) computer landscape. I am very curious to see how this story unfolds, because let’s be clear: Facebook’s earning potential is closely tied to its capacity to capture, enrich, and analyze user data.
This initiative – and the Heise ethos in general – underscores that a “respectable” and sober engineering culture does not exclude an explicit normative stance on social and political issues. And is shows that this stance can be translated into technical models, implemented, and shared, both as an idea and as code.
When it comes to analyzing and visualizing data as a graph, we most often select only one unit to represent nodes. When working with social networks, nodes commonly represent user accounts. In a recent post, I used Twitter hashtags instead and established links by looking at which hashtags occurred in the same tweets. But it is very much possible to use different “ontological” units in the same graph. Consider this example from the IPRI project (a click gives you the full map, a 14MB png file):
Here, I decided to mix Twitter user accounts with hashtags. To keep things manageable, I took only the accounts we identified as journalists that posted at least 300 tweets between February 15 and April 15 from the 25K accounts we follow. For every one of those accounts, I queried our database for the 10 hashtags most often tweeted by the user. I then filtered the graph to show only hashtags used by at least two users. I was finally left with 512 user accounts (the turquoise nodes, size is number of tweets) and 535 hashtags (the red nodes, size is frequency of use). Link strength represents the frequency with which a user tweeted a hashtag. What we get, is still a thematic map (libya, the regional elections, and japan being the main topics), but this time, we also see, which users were most strongly attached to these topics.
Mapping heterogeneous units opens up many new ways to explore data. The next step I will try to work out is using mentions and retweets to identify not only the level of interest that certain accounts accord to certain topics (which you can see in the map above), but the level of echo that an account produces in relation to a certain topic. We’ll see how that goes.
In completely unrelated news, I read an interesting piece by Rocky Agrawal on why he blocked tech blogger Robert Scoble from his Google+ account. At the very end, he mentions a little experiment that delicious.com founder Joshua Schachter did a couple of days ago: he asked his 14K followers on Twitter and 1.5K followers on Google+ to respond to a post, getting 30 answers the former and 42 from the latter. Sitting on still largely unexplored bit.ly click data for millions of urls posted on Twitter, I can only confirm that Twitter impact may be overstated by an order of magnitude…
There are many different ways of making sense of large datasets. Using network visualization is one of them. But what is a network? Or rather, which aspects of a dataset do we want to explore as a network? Even social services like Twitter can be graphed in many different ways. Friend/follower connections are an obvious choice, but retweets and mentions can be used as well to establish links between accounts. Hashtag similarity (two users who share a tag are connected, the more they share, the closer) is yet another method. In fact, when we shift from interactions to co-occurrences, many different things become possible. Instead of mapping user accounts, we can, for example, map hashtags: two tags are connected if they appear in the same tweet and the number of co-occurrences defines link strength (or “edge weight”). The Mapping Online Publics project has more ideas on this question, including mapping over time.
In the context of the IPRI research project we have been following 25K Twitter accounts from the French twittersphere. Here is a map (size: occurrence count / color: degree / layout: gephi with OpenOrd) of the hashtag co-occurrences for the 10.000 hashtags used most often between February 15 2011 and April 15 2011 (clicking on the image gets you the full map, 5MB):
The main topics over this period were the regional elections (“cantonales”) and the Arab spring, particularly the events in Libya. The japan earthquake is also very prominent. But you’ll also find smaller events leaving their traces, e.g. star designer Galliano’s antisemitic remarks in a Paris restaurant. Large parts of the map show ongoing topics, cinema, sports, general geekery, and so forth. While not exhaustive, this map is currently helping us to understand which topics are actually “inside” our dataset. This is exploratory data analysis at work: rather than confirming a hypothesis, maps like this can help us get a general understanding of what we’re dealing with and then formulate more precise questions from there.
When Lawrence Lessig famously stated that “code is law”, the most simple and striking example was AOL’s decision to – arbitrarily – limit the number of people that could log into a chat room at the same time to 23. While the social consequences of this rule were quite far-reaching, they could be traced to a simple line of text somewhere in a script stating that “limit = 23;” (apparently someone changed that to “limit = 36;” a bit later).
When starting to work on a data exploration project linking Web sites to Twitter, I wasn’t aware that the microblogging site had similar limitations built in. Somewhere in 2008, Twitter apparently capped the number of people one can follow to 2000. I stumbled over this limit by accident when graphing friends and followers for the 24K+ accounts we are following for our project:
This scatterplot (made with Mondrian, x: followers / y: friends) shows the cutoff quite well but it also indicates that things are a bit more complicated than “limit = 2000;”. From looking at the data, it seems that a) beyond 2000, the friend limit is directly related to the number of followers an account has and b) some accounts are exempt from the limit. Just like everywhere else, there are exceptions to the rule and “all are equal before the law” (UN Declaration of Human Rights) is a standard that does not apply in the context of a private service.
While programmed rules and limits play an important role in structuring possibilities for communication and exchange, a second graph indicates that social dynamics leave their traces as well:
This is the same data but zoomed out to include the accounts with the highest friend and follower count. There is a distinct bifurcation in the data, two trends emerging at the same time: a) accounts that follow the friend/follower limit coupling and b) accounts that are followed by a lot of others while not following many people themselves. The latter category is obviously celebrity accounts such as David Lynch, Paul Krugman, or Karl Lagerfeld. These brands are simply using Twitter as a one-to-many medium. But what about the first category? A quick examination confirms that these are Internet professionals, mostly from marketing and journalism. These accounts are not built on a transfer of social capital (celebrity status) from the outside, but on continuous cross-platform networking and diligent posting. They have to play by different rules than celebrities, reciprocating follower connections and interacting with other accounts to abide by the tacit rules of the twitterverse. They have built their accounts into mass media as well but had to work hard to get there.
These two examples show how useful data visualization can be in drawing our attention to trends in the data that may be completely invisible when looking at the tables only.
I just saw that the good people from sociomatic have prepared a nice little slideshow on how to use gephi to analyze social network data extracted from Facebook (using netvizz). This is a great way to start playing around with network analysis and the slides should really help with the first couple of steps…
2 Comments Posted by Bernhard on November 2nd 2010 @ 2:42 am
When it comes to scrutinizing companies for their actions and policies concerning control over information, privacy issues, and market dominance in areas related to public debate, large media conglomerates have been the traditional objects of analysis. More recently, Internet giants such as Google and Facebook have been critically examined and when the hype levels off, Twitter will probably be the next on the list. Malcolm Gladwell’s recent piece in The New Yorker may very well be an indicator of things to come.
Whether the issues related to “social media” are important or not, I have the feeling that the debate overshadows questions and problem fields that may in fact be much more important. The most obvious case, in my view, is the debate on privacy on Facebook. While the matter is not irrelevant, I think that e.g. present and future state-run information systems such as the french EDVIGE, a central police database that assembles all kinds of personal information concerning select persons “of interest”, have been overshadowed by debate on whether your employer can see the pictures that document your drinking binges after somebody (you?) put them on the ‘Book. There is a certain disequilibrium in how Internet researchers and critics distribute their attention that has allowed all kinds of things to pass below the radar. But there is one event that has really shook me up recently, both because of its importance and the lack of outcry it garnered, at least in my echo chamber: the acquisition of the Reuters group by the Thomson corporation in 2008 and the creation of Thomson Reuters, an information giant second to none.
I have stumbled upon Thomson Reuters a couple of times over the last years: first, when I researched the history of citation indexing, I learned that Thomson Scientific had bought the Institute of Scientific Information (and their Web of Science citation index megabase from which things like the notorious Impact Factor are calculated) in 1992; then again when I noticed that the ClearForest API for term extraction had be renamed, remodeled, and rebranded as OpenCalais after Reuters bought the company in 2007; finally, last year, when I noticed that the Reuters video platform appeared more and more often in articles and links. When I finally started to look a little closer (NYSE:TRI) I was astounded to find a company with a market cap of $31B, annual revenues of $13B, and 55K+ employees all over the world. Yes, this is no Apple big, but still very, very big for a company that sells information.
I knew Reuters from my studies in communication science as the world’s biggest news agency (with roughly one and a half competitors: Associated Press and Agence France Presse) but I had never consciously registered the Thomson company – a Canadian Family business that went from the media (owning the London Times at one point) to publishing before transforming itself in a rather risky move into a digital information broker for all kinds of special fields (legal, health, finance, etc.). Reuters was a perfect match and I really wonder how that merger went through without too much hassle from the different regulatory bodies. Even more so when I found out that Reuters actually had devised a very spicy regulatory clause when it made its IPO in 1984: to avoid control over such a central source of information, no single shareholder would be allowed to hold more than 15% of the companies stocks. Apparently, that clause was enacted at least once when Murdoch’s News Corporation (already holding 15%) bought a competitor that also owned a piece of Reuters and consequently had to shed stock to stay below the threshold. The merger effectively brought the new Reuters Thomson under full control (53%) of The Woodbridge Company, a private holding that represents the Thomson family.
Such control over a news agency (and the many more specialized services that are part of the giant’s portfolio) should give us pause in the best of times when media companies are swimming in resources, are able to pay good money for good journalism, and keep their own network of correspondents. But recent years have seen nothing but cost cutting in journalism, which has led to an even greater reliance on news agencies. I wager that Google News would work a lot less well if people actually started to write their own copy instead of remodeling Reuters’ and AP send outs.
But despite these rather traditional – but nonetheless crucial – concerns over media ownership and control, there is a second point that is somewhat closer to my area of expertise. I have recently been thinking a lot about how to best phrase criticism of the assumption that digital networks necessarily lead to decentralization. Thomson Reuters – but also other information giants such as Google and Facebook – is a great example for how digital technologies can lead to quite impressive cost reductions for economies of scale and, consequently, market concentration. These arguments should be taken into account:
- While the barriers of entry to the Internet are really low (you can have your own blog in minutes), scaling up to millions of visitors is a real challenge. Building your own datacenter is a real bump in the learning curve and to get over it, you need to make certain investments. But once you pass that bump, scaling suddenly becomes cheaper again because you have the knowledge ressources and experience that can now be applied to make the datacenter grow. One of Google’s strengths lies in this area and this immensely facilitates branching out into new information ventures. The same goes for Thomson Reuters: they master platform technology and distribution technologies for all kinds of contents and they can build on that mastery to add new things to serve information to a globalized planet. To use the language of the long tail: there may be more special interest information that can find an audience with shelve space becoming effectively unlimited; but there is also no longer a need for more than one shelve.
- The same goes for a more elusive matter: the mastery of information. The database techniques and indexing tools we use to store information – as well as the search and data-mining algorithms – can be very easily transported from one domain to the next. While it may be (very) difficult to create useful search tools for medical information, once you have built them it is rather easy to adapt these tools to, let’s say the legal domain. Again, this is what makes Google strong: basic search technology can be applied to advertising, books, mail, product prices, and even video if you can do automatic transcription. With the acquisition of ClearForest, Thomson Reuters has class-leading in-house data-mining and this is not something you can get by simply posting a couple of job ads in the local newspaper. Data-mining is extremely useful in areas where fast decision-making is crucial but also when it comes to building powerful search tools. Again, these techniques can be applied to any number of fields and once you have the basics right you can just add new domains with very little cost.
These two points go a far way in explaining why the Internet has seen the lightning fast emergence of network giants over the last couple of years. I really don’t want to postulate yet another “law” of the Net but I believe that there is something to this idea of the bump: it’s easy to have a basic presence on the Web but it’s hard to scale up to a large audience and to use advanced computational techniques; but one you pass the bump, the economies of scale kick in and from there it seems like there are no barriers to growth. The Thomsons have certainly made that bet when they acquired Reuters and so far, it seems to work out quite nicely for them.
I hope we can find a means to extend critique from questions of ownership into the heart of the (informational) beast and come up with better ways to understand how the still ongoing shift to exclusively digital information affords new means of handling and exploiting that information – with organizational, economic, and political consequences. While that work is starting to take shape for consumer companies like Google that are in the spotlight, there is surprisingly little on invisible network giants like Thomson Reuters that cater mostly to professional clients.
One Comment Posted by Bernhard on October 14th 2010 @ 12:14 am
Yesterday, Microsoft announced another step in their “long-term partnership” with Facebook. The two companies have had close ties since Microsoft invested a hefty sum in Facebook in 2007 and the former has managed advertisement on the latter’s site for quite a while. The “next step” will basically add a “social layer” to Bing search results (go to Ars Technica for a writeup or All Things Digital for a liveblog of the PR event) and this is actually a pretty big thing. Google has certainly taken contextual information into account when deciding which results to show and how to rank them: physical location, search history, and gmail contacts have been part of that process for a while, but the effects have been rather subtle.
Bing’s new features basically use the same technical layer as the Facebook boxes that popped up all over the Web about half a year ago (most modern browsers have plug-ins that allow you to block those by the way). If Bing detects the Facebook cookie while you’re on their site and adds a couple of features that allow you to interact with “friends” more easily. There are some basic convenience features but it is the “liked results” that are the most remarkable: results will use your contact’s “likes” to rank results. While we will have to wait to see how these features will pan out, social search may look something like this:
In this example, the first result is the announcement of a news article on the release of the DVD version of Iron Man 2 and this would be hardly a top-ranked result without the social layer. If Bing continues to make inroads on Google, the “like” button may take on additional importance for driving traffic and marketeers will most certainly device new ways to get people to “like” stuff – e.g. “press the button and win a free t-shirt”.
Cas Sunstein’s arguments on the dangers of echo chambers – “incestuous amplification” in social groups – will certainly be taken up again, and perhaps rightfully so: while the Internet remains a beautifully heterogeneous mess, the algorithmically sustained support for the logic of homophily (“birds of a feather…”) that can be observed in more and more places on the Web merits critical examination. While Diana Mutz’s work makes the inconvenient argument that “hearing the other side” of political debate may actually lead to less political engagement, our representative systems of democratic governance require a certain willingness to accept different political viewpoints (that always float on less clearly delineated cultural sensibilities) as sincere and legitimate. Also, adding a “friend” dimension to yet another dimension of the Web could be seen as a further reduction of the “publicness” that, according to Michael Schudson, caracterizes working democratic discourse. Being able to dissociate ourselves from our private entanglements and take into account the interests of those who do not ressemble us is perhaps the central prerequisite to successfully navigating a smaller planet.
Bing’s new features are certainly not the end of life as we know it but I believe that the privacy question – as important as it is – is covering a series of more difficult problems that sit at the heart of political life in the age of the Internet…
One Comment Posted by Bernhard on October 10th 2010 @ 1:38 am
What is a link? From a methodology standpoint, there is no answer to that question but only the recognition that when using graph theory and associated software tools, we project certain aspects of a dataset as nodes and others as links. In my last post, I “projected” authors from the air-l list as nodes and mail-reply relationships as links. In the example below, I still use authors as nodes but links are derived from a similarity measure of a statistical analysis of each poster’s mails. Here are two gephi graphs:
If you are interested in the technique, it’s a simple similarity measure based on the vector-space model and my amateur computer scientist’s PHP implementation can be found here. The fact that the two posters who changed their “from:” text have both of their accounts close together (can you find them?) is a good indication that the algorithm is not completely botched. The words floating on the links on the right graph are the words that confer the highest value to the similarity calculation, which means that it is a word that is relatively often used by both of the linked authors while being generally rare in the whole corpus. Elis Godard and Dana Boyd for example have both written on air-l about Ron Vietti, a pastor who (rightfully?) thinks the Internet is the devil and because very few other people mentioned the holy warrior, the word “vietti” is the highest value “binder” between the two.
What is important in networks that are the result of heavily iterative processing is that the algorithms used to create them are full of parameters and changing one of these parameters just little bit may (!) have larger repercussions. In the example above I actually calculate a similarity measure between each two nodes (60^2 / 2 results) but in order to make the graph somewhat readable I inserted a threshold that boils it down to 637 links. The missing measures are not taken into account in the physics simulation that produces the layout – although they may (!) be significant. I changed the parameter a couple of times to get the graph “right”, i.e. to find a good compromise between link density for simulation and readability. But look at what happens when I grow the threshold so than only the 100 strongest similarity measures survive:
First, a couple of nodes disconnect, two binary stars form around the “from:” changers and the large component becomes a lot looser. Second, Jeremy Hunsinger looses the highest PageRank to Chris Heidelberg. Hunsinger had more links when lower similarity scores were taken into account, but when things get rough in the network world, bonding is better than bridging. What is result and what is artifact?
Most advanced algorithmic techniques are riddled with such parameters and getting a “good” result not only implies fiddling around a lot (how do I clean the text corpus, what algorithms to look for what kind of structures or dynamics, what parameters, what type of representation, here again, what parameters, and so on…) but also having implicit ideas about what kind of result would be “plausible”. The back and forth with the “algorithmic microscope” is always floating against a backdrop of “domain knowledge” and this is one of the reasons why the idea of a science based purely on data analysis is positively absurd. I believe that the key challenge is to stay clear of methodological monoculture and to articulate different approaches together whenever possible.
Endlich verstehe ich das! i.imgur.com/sJ597W4.gifv
Yann LeCun (Facebook AI Research), Eric Horvitz (Microsoft Research) and Peter Norvig (Google) had a Reddit AMA ses… twitter.com/i/web/status/9…
Facebook has revoked page insight access for pages you don't have a token for. The corresponding file output in… twitter.com/i/web/status/9…
Saturday geekery: an introduction to Facebook's MyRocks MySQL storage engine code.facebook.com/posts/19025104…
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