How many is a crowd?

According to a recent Wall Street Journal article, it's hard to tell how many centenarians there are. There are several reasons for this, but paradoxically, one reason is that there aren't that many of them. As a result, it's difficult to make a generic statement like "There are N people in this county over 100 on Social Security," because N is liable to be 1 or 2, in which case you've just told the world that those particular people are on social security. One comes to value one's privacy as one grows older.

The same situation arises in tabulating election results in sparsely-populated areas. Announcing that six people in the county voted for candidate A and two voted for candidate B is somehow different from announcing six thousand and two thousand. Granted, in a county with eight voters, lack of anonymity kind of goes with the territory.

So at what point do we start to feel that aggregate results are comfortably anonymous? There's almost certainly no single point, and I'm being deliberately vague with "comfortably anonymous", but it's an interesting question. Discussion of web communities often revolves around social networks, in which anonymity is specifically not such a concern, or "megacommunities", which are big enough that aggregates are almost certainly comfortably anonymous.

But even on the web, if you slice out a small enough niche, the question can come up. If I hear that forty anonymous members of the left-handed Dutch-speaking pigeon fancier's society are in favor of some proposition, I may not have too much trouble figuring out who that is.

What's a community, anyway?

Earl comments, regarding megacommunities:

You need a special and somewhat sloppy definition of "community" to avoid oxymoronity.

Or in other words, how can you call something with a million or more people in it a "community"?

Certainly the Los Angeles Department of Public Works has no trouble doing so, nor did the European Community, nor do people referring to the scientific community (one hopes that there are at least a million scientists in the world). On the other hand, a horde of 100 million Skype users doesn't exactly conjure up images of neighbors strolling through the park greeting each other with friendly hellos.

If the working definition of "the registered users (or paying customers) of a given service" misses out too much of the "people living and working together" aspect of community, what is it we're trying to capture here? I can think of three aspects:

• Belonging: People will say, for example, "I belong to Facebook" (amusingly, people also appear to be saying "All your X are belong to Facebook", for various X. Ah, the classics.)
• Self-identification: I could define a "community" of, say, people with last names with an even number of letters, but that doesn't make that group a community.
• Interaction: This, I think, is what gives online communities of whatever size their best claim to "community", and why I didn't mention things like banks with millions of online customers as megacommunities.

The whole point of many of the megacommunities I mentioned, and a major point of at least most of them, is that someone belonging to such a community can easily contact another member. Even if they have never met before, they will have something in common by virtue of belonging to the same community.

Whether a given person will actually do this and whether anything will come of it are separate questions, but so are they in a "real" community.

Megacommunities

How many communities have more than a million members? I'll call such a community a megacommunity. I see that the word is already in use in a slightly different sense (see here for example), but all words have multiple senses and I can't think of anything better.

First, there are geopolitical communities such as nations, provinces, states or what-have-you and large cities. There are around 150 countries with population over 1 million and hundreds of urban areas that size (just how many depends on how you count). Numbers concerning religious affiliation are even more open to interpretation, but it seems safe to say that there are dozens but not hundreds of religious megacommunities.

What about corporations? WalMart now has 1.9 million employees. China National Petroleum has just over a million. And that's it.

Now what about web communities? If anyone knows a comprehensive list of online communities ranked by number of registered users -- and it's probably out there, I'd be glad to see it [In other words, I did a very quick Google and punted]. Here's what I got just by listing sites off the top of my head or as I ran across references to them, and quickly checking first the site's home page (generally not too helpful) then Wikipedia and then Google if neither of those seemed to work. Please take these figures with at least a grain of salt:

• MySpace has about 300M registered users (Wikipedia)
  
• Orkut 67M (possibly including at least one automagically-signed-up user who was just trying to find out how many users there were) (Wikipedia)Facebook has about 60M "active" users (Wikipedia)
  
• Photobucket claims 58M on its home page, Wikipedia quotes a recent Fortune article giving 36M.
  
• Kodak Gallery (formerly Ofoto) has 20M users (Wikipedia)
  
• LinkedIn 17M (web site)
  
• Second Life claims 11M residents on its FAQ list
  
• AOL around 10M subscribers and dropping rapidly (Computerworld article)
  
• flickr had about 8M registered users in May 2007 (TechNewsWorld article)
• Near misses
• Shutterfly had around 0.8M "transacting users" in Q307 (Shutterfly quarterly report)
• YouTube has 0.5M registered users (Wikipedia)
• Incomplete information (OK, I punted again)
  
• Technorati indexes gobs and gobs of blogs, but it's not clear how many registered users it has
• Skype shows around 10M people online at any given time and I've seen 100M total users claimed.
  
• Some I didn't get around to looking up
  
• Blogger (!)
  
• Amazon
  
• EBay
  
• Gmail
• Yahoo!
• Hotmail
  
• Wikipedia
• deli.cio.us
• StumbleUpon
• digg
• Netflix
• jaxtr
  
• Any MMORPGs

It's a big world out there. I hadn't even heard of one or two of the names mentioned until I started digging. There are certainly more online megacommunities than religious ones. There may be or may soon be more than there are national megacommunities. Certainly there are online communities that would rank high on the list of countries by size.

Does this mean that traditional structures are on the verge of being overrun by virtual ones? Well ... first, many of the figures above should be taken with a grain of salt. At the very least, one needs to distinguish between everyone who's ever registered and everyone who's actively participating (Shutterfly could and probably does claim a considerably higher number of registered users than it does "transacting users").

It's also very easy (and sometimes useful) to belong to multiple online communities. It's possible to practice more than one religion or be a citizen of more than one country, but it's not the norm and the practical limit is not much more than one.