The Basement

I heard from Brains on Fire's Spike Jones who heard from AdPulp that Technorati's David Sifry posted his latest State of the Blogosphere report. This made me think of the Spam in the Blogosphere paper published by CGM monitoring firm Umbria Communications in December. Hmmmm.

Mr. Sifry tells us that there were 8M blogs in March, 2005; about 18M in October, 2005; and about 27M in January 2006. Doubling every 5ish months, he says. After a little quick and dirty curve fitting, I calculated that this means that, according to Mr. Sifry's data that the number of blogs in the blogosphere (at least the ones tracked by Technorati) increase by 12.75% each month. Impressive.

In its comprehensive report on the state of splogs, Umbria Communications says that 2% of blogs were splogs in March, 2005; 13% in October, 2005; and 20% in December 2005. Again, some quick math yields an estimated increase in the percentage of spam blogs at 31% per month. Equally impressive.

But wait, I thought to myself, if the percentage of spam blogs is growing, and the number of blogs is growing, then the growth rate of the number of spam blogs would be even higher. Indeed it is. According to Umbria's report, the number of spam blogs has grown at a rate of 48% monthly since March, 2005. Ummm, super impressive. (or depressive, depending on perspective)

The thing that really struck me is that if spam blogs are growing at such a fast rate, and we haven't seen an increase in the rate of growth of the Blogosphere in general, then what does that mean for the growth rate of non-spam blogs?

Well, let's take a look at Mr. Sifry's blog growth graph.

(click image for larger view)

I created an approximation of Sifry's trend and carried it forward (assuming a constant rate of growth of 12.75%) out to May, 2006. I then created an approximation of Umbria's splog trend for the same time period, using a constant 31% increase in the percent splog (same as 48% increase in number of splogs.) Finally, I subtracted the number of Umbria splogs from the number of Sifry blogs to yield an approximate number of non-spam splogs.

Then I graphed it and got this...

(click image for larger view)

Yulp, you're reading it right. Assuming that both Sifry and Umbria are accurate and that these growth rates are remaining constant - the non-spam Blogosphere has peaked in size and is now contracting. Furthermore, by March, blog spam will represent half of all blogs.

Anybody want to take a stab at what the heck is going on here?