Sunday, November 04, 2007

The Personal Network Effect

The presumption in the design of most networks is that the value of the network increases with the number of nodes in the network. This is known as the Network Effect, a term that was coined by Robert Metcalfe, the founder of Ethernet.

Image source

It is therefore tempting to suggest that a similar sort of thing holds for members of the network, that the value of the network is increased the more connections a person has to the network. This isn't the case.

Each connection produces value to the person. But the realtive utility of the connection - that is, its value compared to the value that has already ben received elsewhere - decreases after a certain point has been reached.

The reason for this is that value is derived from semantic relevance. Information is semantically relevant only if it is meaningful to the person receiving it (indeed, arguably, it must be semantically relevant to be considered information at all; if it is not meaningful, then it is just static or noise).

Semantic relevance is the result of a combination of factors (which may vary with time and with the individual), according to whether the information is:
  • new to the receiver (cf. Fred Dretske Knowledge and the Flow of Information)
  • salient to the receiver (there are different types of salience: perceptual salience, rule salience, semiotic salience, etc)
  • timely, that is, the information arrives at an appropriate time (before the event it advertises, for example) - this does not mean 'soonest' or 'right away'
  • utile, that is, whether it can be used, whether it is actionable
  • cognate, that is, whether it can be understood by the receiver
  • true, that is, the information is consistent with the belief set of the receiver
  • trusted, that is, comes from a reliable source
  • contiguous, that is, whether the information is flowing fast enough, or as a sufficiently coherent body
Because of these conditions, the value of each new piece of information, on average, will decrease relative to its predecessors. At a certain point, the value of the new information will be such that it actually detracts from the value of the information already received (by, say, blocking it, distracting one's attention from it, contradicting it, and the like).

For example, suppose someone tells you that the house is on fire. This is very relevant information, and quite useful to you. Then another person tells you on fire. It's useful to have confirmation, but clearly not as useful as the first notice. Then a third and a fourth and a fifth and you want to tell people to shut up so you can hear the next important bit of information, namely, how to get out.

This is the personal network effect. In essence, it is the assertion that, for any person at any given time, a certain finite number of connections to other members of the network produces maximal value. Fewer connections, and important sources of information may be missing. More connections, and the additional information received begins to detract from the value of the network.

Most people can experience the personal network effect for themselves by participating in social networks. One's Facebook account, for example, is minimally valuable when only a few friends are connected. As the number grows over 100, however, Facebook begins to become as effective as it can be. If you keep on adding friends, however, it begins to become less effective.

This is true not only for Facebook but for networks in general. For any given network, for any given individual in the network, here will be a certain number of connections that produces maximum value for that member in that network.

This has several implications.

First, it means that when designing network applications, it is important to build in constraints that allow people to limit the number of connections they have. This is why the opt-in networks such as Facebook produce more value per message than open networks such as email. Imagine what Twitter would be like is anyone could send you a message! The value in Twitter lies in the user being able to restrict incoming messages to a certain set of friends.

Second, it provides the basis for a metric describing what will constitute valuable communications in a network. Specifically, we want out communications to be new, salient, utile, timely, cognate, true and contiguous.

Third, it demonstrates that there is no single set of best connections. A connection that is very relevant to one person might not be relevant to me at all. This may be because we have different interests, different world views, or speak different languages. But even if we have exactly the same needs and interests, we may get the same information from different sources. By the time your source gets to me, the 'new' information it gave you might be very 'old' to me.

We see this phenomenon is web communities. Dave Warlick today posted a link to a video produced by Michael Wesch's Cultural Anthropology students at Kansas State University. Warlick obviously does not read OLDaily because I linked to the site two weeks ago. Warlick credits John Moranski, a school librarian from Auburn High School and Middle School in Auburn, Illinois (no link, which means he probably told him about it in person or by email). Warlick's link, therefore, is of little value to me; it's old news. However, to many of his readers (specifically, those who don't read me), this will be new. And hence he is a valuable part of their network.

Now here is the important part: the people who read Warlick don't need to read me (at least with respect to this link). They are getting the same information either way. There is no particular reason to select one source over another. Warlick may be part of his readers by accident (he is the first ed tech person they read, for example) or he may be more semantically relevant to them for other reasons: he is a folksy storyteller, he writes in a simple vocabulary, they have met him personally and trust him, whatever.

One final point: if we change the way we design the network, we can change the point of maximal value:

It is toward this effect that much of my previous writing about networks has been directed. How can we structure the network in such a way as to maximize the maximal value? I have suggested four criteria: diversity, autonomy, openness, and connectedness (or interactivity).

For example, networks that are more diverse - in which each individual has a different set of connections, for example - produce a greater maximal value than networks that are not. Compare a community of people where people only read each other. You can read ten people, say, of a fifty person community, and hear pretty quickly what every person is thinking. But reading an eleventh will produce almost no value at all; you will just be getting the same information you were already getting. Compare this to the value of a connection from outside the community. Now you are reading things nobody else has thought about; you learn new things, and your comments have more value to the community as a whole.

It is valuable to have a certain amount of clustering in a network. This is a consequence of the criterion for semantic relevance. This is that people like Clark are getting at when they talk about the need for a common ground, or what Wenger means by a shared domain of interest. However, an excessive focus on clustering, on what I have characterized as group criteria, results in a decrease in the semantic relevance of messages from community members.


  1. A bit obvious, but I had never thought of it in this way before (so not so obvious). This neatly explains why I hardly ever participate in a language learning forum I used to be heavily involved in (although still monitor via RSS).
    The infomation coming in becomes less relevant as I learn the language (assuming I master the language, the information becomes complety irrelevant).

  2. If it seems obvious then my objective in writing this post has been met.

  3. If it seems obvious then my objective in writing this post has been met exactly! it was only obvious after I read it :)

  4. A very good post, and of course it was obvious (after the fact). I think I'll review my feeds and see if I can diversify them a bit more.

  5. A fairly accurate perspective... but it does miss the importance of "node quality" - not all network nodes (people in your personal network) are equal!

    You can maximise the maximal value of your personal network by selecting from all those nodes available a subset of high quality members - for example, original thinkers, accomplished creators, or knowledgeable analysts.

    Whether your network is in the blogosphere or in Facebook, it's possible to create "garbage networks" - networks of people who only serve to reinforce each others' misconceptions.

    Some of the most useful nodes, therefore, are "synthesisers" - people who neither trust everything they read (no matter how reputable the source), nor think their own ideas are infallible, but instead provide analysis that is both accurately critical and humbly reflective.

    At the other extreme, I value "specialists" - people who are terrific in just one or two things, and are prepared to argue a case from one (or another) perspective. These are often the people who are the best creators or discoverers of original content... but due to their particular specialisations, not always the best broad analysts across a full range of issues.

    The combination of a select group of first-class synthesisers and specialists makes my personal network as strong as possible, for me. :)

  6. Leonard, this is a very interesting comment, but one with which I am in disagreement.

    I reject the idea that there are 'quality' nodes in a network.

    First of all, it relies on an inference that is unwarranted. Nodes are selected for linkage according to properties of the network and of the messages - in other words, from properties that can be 'seen' by the node. There is no way for a node to be able to evaluate some sort of property, 'quality', over and above the messages and information received.

    Second, the presupposition is that only information that is received from the best and most reliable source is valuable to the receiver. This is totally untrue! We need to rely on people who are not expert, and not only on the experts. *every* point of view is valuable, because it is only through amassing every point of view that we can obtain a complete picture.

    If you think about how much we learn from our friends in the pub, our children, the mentally challenged, our students, and even our pets, you will realize that it is not quality at all that determines our choice of network connections.

  7. Very interesting post, Stephen. In addition: people 'belong' to different networks. The 'nodes' of these networks come together in social networking applications. For example: one of the tools I use is LinkedIn. I have almost 180 connections in LinkedIn. But it is hard to group these connections per network. Therefore social networking tools should enable diversification of networks. So you can link 'nodes' to different networks. Imho most of the current applications need improvement as far as diversification is concerned.

  8. Thanks Steve for another lesson about networked learning. It is tempting to assume that we should limit our connections after reading this post. Then I thought what we should really limit is the quality of the information that are translated to us. Although the volume of information may exceed and makes the marginal benifit of any more information become negative. But this is seldom the case, because we usually can control the volume of information that we consume everyday. So even the volume may sometimes exceed to an unbearable extent, it is seldom so. We are more apt to waste our time consuming the repeated information. So, the question seems to be how to control the quality of the flow of information, not how to control the amount of connections. Because we could connect to a large pool of nodes by weak connections. These nodes may only transfer a minor amount of information to the node, but the don't transfer so much information as your primary pools of nodes do. These primary nodes, in my opinion, are what we should concentrate on. But I think in a micro level, we should come up with an efficient manage system so that we could manage all the pools of nodes we connected to. So, for some remote pools, we don't have to control the number of the nodes: the more the better. Some valuable information may emerge from these pools. But for some strong connected pools, we should filter and be choosy, for they are the source of the biggest portion of our information flow, if we donot control them well, they will overwhelm us.

  9. Not so obvious but very pertinent.

    'e'ffect becoming networked 'a'ffect.

    The switch between each paradigm is the interesting factor and perhaps it's about networks reaching a zenith point where they devolve upon realization that participation doesnt equate to fame-whoring.

    Feeding the hand that bites.


  10. For some the personal networked effect is closer to home .....

    "Kids today. They have no sense of shame. They have no sense of privacy. They are show-offs, fame whores, pornographic little loons who post their diaries, their phone numbers, their stupid poetry—for God’s sake, their dirty photos!—online. They have virtual friends instead of real ones. They talk in illiterate instant messages. They are interested only in attention—and yet they have zero attention span, flitting like hummingbirds from one virtual stage to another....."

    Courtesy of Emily Nassbaum -

  11. This conversation puts me in mind of Malcolm Gladwell's Tipping Point. Those social personalities he writes of are active agents on the internet.
    Of course my book is nowhere to be found this evening, but some of the buzz words that made a lasting impression were salesman, maven, connector etc. Each has a part of the social equation that becomes the spread of culture, information, and focused energy across the universe of available contacts.

    Also, the social networks are what they are by perspective. My internet is a source of information, social contact, professional development, invention, and entertainment. One son takes web vacations from his military life. My older son shops the web--comparison shopping and locating items to collect and own.

    My husbands view of the web is pragmatic. "What can it do? Can it bring in the wood, fix the car? No? Well, somebody around here has to get off the damn computer and do those things!"

    How ever it works, I count myself lucky. No matter how obscure or popular, fleeting or enduring, my interest in topic or activity may be, the internet nourishes me socially and academically in ways that my family and work community does not be able to do. I count this access as something very important in my life.

  12. a piece of the problem to solve here is how to efficiently partition your network so that you hit the "right" people for whatever query or note you want to send to them.

    setting aside for a moment the question of whether 150 or 1500 or 15000 is the right number to aim for, seems to me that systems like LinkedIn that let you say "send this personalized message to all my healthcare contacts in New Jersey and upstate New York" give you the possibility to extract maximum value from very large networks. no one would think it was spam since no individual message is replicated to too many people.


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