Roger attended last week a panel discussion with some old-media guys and of course the inevitable question came up. “How popular is a single blog” or “what's the equivalent to the ‘watch-figures' in TV and newspapers”. Those figures seem to be important to old-school-media people, as they want something to compare, but especially for blogs, there are quite some pitfalls in doing such measurements.

But first and most important, most bloggers do not care that much about how much people they reach. They blog, because it's fun and are happy if they reach their friends. This of course doesn't apply to “professional” bloggers, which do rely on sellable pageviews for their income.

Basically, there are 2 different types for measuring blog popularity: “How many people are referring to my blog” and “How many people are reading my blogs”.

The first one is what technorati and therefore the Swiss Top 100 Blogs do: Count the amount of blogs which refer to a single blog. One disadvantage of this is, as Roger noted, that old blogs have much more backlinks than new ones. It's not that obvious on the Swiss Top 100 list, there are quite a few “new” blogs in the top 20 (new = started this year), but nevertheless the problem exists. This could be solved with a “how many new links in the last x days” approach, to see which blogs are currently popular in the blogosphere. The Top 100 List provides this for the last 20 days (note that the technorati API interface currently stalls somehow, it doesn't seem to be updated since approx. 2 weeks).

Furthermore, do you count the amount of blogs linked to you, or the amount of links. Difference is, that when I quote you twice you only get one hit with the first method, but two with the second (the “blogs” vs. “links” column in the top 100 list). Technorati rates “amount of blogs” before “amount of links”.

The general problem in my opinion with this is, that there may be popular blogs with not that much backlinking (because for example their target audience doesn't blog) and they fall through this measurements.

The other approach with counting pageviews has even more problems. Basically, what do you count as page view? In the times before RSS this was quite easy, every html page visited = one page view. Today with the rise of RSS aggregators that doesn't hold up anymore. I read a looot of blogs only through my RSS reader and go very seldom to the actual page (full feeds ahoi, but don't try to get me to your site with only providing partial feeds, you will sooner gone from my list, than that I visit your page more). Now, my aggregator gets the feed every half hour by default. Assuming I'm 10 hours online, this counts to 20 hits, but if you didn't update your blog, I won't even recognize it. The same problem with counting “visits”. Webalizer for example has a default timeout of 30 minutes (AFAIK), so webalizer does count that as 20 visits (not sure what happens with edge-cases like this, but anyhow). I checked with my webalizer stats, what's the difference of webalizer visits if I count RSS feeds or not. For October, I had 1793 visits a day without RSS feeds and 4455 with RSS feeds. Not even close the same :)

The problem gets “worse” with all the online aggregators like Planet PHP or Bloglines. Planet PHP is read by thousands of people daily and all my PHP related posts go there, as well. Unless Planet readers want to comment on my post, they almost certainly don't come to my blog. And the Planet PHP feed is aggregated by even more sites. The same with Bloglines, according to my log file, 134 have subscribed my blog there, which only gives me one hit in the log files.

In short, counting pageviews for comparing different blogs is almost impossible, it may give you a broad view, which blogs are read often, but that's about it. It may still be a good way for yourself to see the general trend of your user base.

One other way to quickly check, if a blog has an interested and active user base is to look at its comments. Almost no comment all the time: Not many people find it interesting (or the blogger is just not writing stuff worth to comment). Some comments now and then: People read it, are interested and take the time to add their opinion.

As you can see, there's no tool nowadays to really compare the “importance” of one blog to another, all the ways to count that have their pros and cons and that's also the reason, why there is no ultimate “most important blogs” list. Old media people may have a problem to digest that, they're used to their WEMF figures and obviously need something to compare and to estimate the “threat” of the blogs to their domain….