I did go looking for those numbers but sadly I don’t think I have that much detail available to me.

Now go enjoy your holiday! I’m about to head out to exercise a little liberty myself.

In the past, my guesstimate (based on info I’d seen) was that Bloglines probably represented 25% to 40% of the subscribers for a given blog. So my guess was that I had around 400 to 500 readers-via-feed when (I thought) Bloglines showed around 125.

If Bloglines now represents half of total feed subscribers for typical blogs, that’s a change–and in some ways I’d guess that web-based aggregators have grown at the expense of other aggregators, but that’s also only a guess.

It’s only one number. Most other “reach” numbers that have been suggested are, I believe, far more volatile and much more inclined to “favor the favorites”–e.g., Technorati, Pubsub, etc.

I’m using it by itself as a plausibly representative number: That is, chances are that a blog with, say, 10 Bloglines subscriptions, when compared in actual readership with a blog with 1,000 Bloglines subscriptions, is likely to have “a lot fewer” readers–maybe (probably) not exactly 1%, but probably somewhere between 0.25% and 10%. I just can’t imagine any reason why that would not be the case, why some blogs would have disproportionate numbers of non-Bloglines subscribers.

This year’s “research” really won’t be focused on reach. I’m using Bloglines count to roughly identify “the great middle”–a starting pool of roughly 30-50% of the plausible candidates, eliminating the “top” and “bottom.” Within that pool, I certainly don’t expect to use Bloglines count as a directly meaningful figure. But I do claim that blogs with a very large number of Bloglines subscribers are likely to be the most widely read blogs, and that blogs with a very small number of Bloglines subscribers are likely to be the least widely read. Within the great middle, all bets are off. [Right now, the "great middle" is 16 to 689. Those numbers will change: I can't possibly do full metrics on that many blogs, particularly now that I'm back full time at work.]

[I will have different sorts of cross-checks. Enough people have responded to my request for May 2006 session-per-day and unique-IP counts to be able to do some correlations, or at least see if correlations make any sense.]

I appreciate your efforts on this topic. I have no doubt that I’ll discover some wonderful new blogs again. But I have to wonder, how truly representative are Bloglines subscription numbers? Now, I fully understand that this is a serious effort to undertake and that this methodological constraint is a real world one. That is, it may be the best that can be currently undertaken based on the technologies that we have at the moment.

I recently signed up for a FeedBurner account for my blog and found out that I had over a hundred subscribers vs. the 61 Bloglines shows me. It also turns out that these numbers are far more volatile than the ones in Bloglines. FeedBurner currently reports 94 where two days ago it was only 88.

According to FeedBurner, Bloglines subscribers account for only 50-53% of my total subscribers. This has stayed at this point for a week now. The interesting thing is my blog is being read in over 20 different feed readers.

I have no idea if the 50% Bloglines numbers hold for most other libloggers are not. It might be interesting if you can get a sample of that sort.

I am not trying to discourage you or diminish your efforts; I truly do appreciate them! I guess I’m just wondering if you aware of this and possibly other confounding variables, and what we can do to assist you in accounting for them?