The Healthcare 100 adds metrics, updates algorithm

We’ve been gratified — more than gratified — at how health and medical bloggers the world over have embraced the Healthcare 100.

Since we launched the Healthcare 100 a little over a year ago, the list has grown to more than 900 blogs — with hundreds of bloggers submitting their own blogs. Many of our favorite blogs display a Healthcare 100 badge on their sites. The list even got a mention in the online Wall Street Journal a while back.

But as they say, with power comes responsibility. Not that we consider the Healthcare 100 all that important in the grand scheme of things — but to the extent people trust in us, we have a responsibility to make the list the best it can be. So, in an effort to create a Healthcare 100 that better reflects the comparative influence of its 900+ listed blogs, we’ve updated our algorithm to incorporate new metrics and to reflect the changing influence of some of our old metrics.

As with the first iteration of the Healthcare 100, we were inspired by Todd Andrlik, who created and maintains the AdAge Power 150. The new metrics we’ve added are, for the most part, the same ones added by AdAge sometime back.

Specifically, they are –

Yahoo InLinks: Yahoo tabulates the number of links to a particular blog with its Site Explorer. The more links, the higher the blog’s score on our 30-point scale.

Technorati Authority and Technorati InLinks: We’ve added two new Technorati-based metrics in addition to the current Technorati Rank metric. Technorati Authority shows the number of unique blogs that have linked to a particular blog over the past six months. Technorati InLinks, like Yahoo InLinks, measure the number of individual links to a blog. For each of the three Technorati metrics, the Healthcare 100 scores blogs on a 20-point scale.

Alexa Rating: Alexa computes traffic rankings by analyzing the Web usage of millions of Alexa Toolbar users. A blog’s Alexa value is determined based on ranges (e.g., top 10,000, top 20,000, etc.), and each range is assigned a number (1 to 20) that is part of the algorithm.

In adding these new metrics, we’ve reduced the relative influence of the existing metrics. We’ve also further reduced the influence of Bloglines, since the importance of this feed reader compared to others, such as Google Reader, has declined over time. Unfortunately, Bloglines is still our best proxy for measuring feed subscribers, since not all blogs use Feedburner and there’s no API to access Google Reader subscribers automatically.

Along with adding and changing the weighting of metrics, we’ve incorporated some cool new features to help you get more out of the Healthcare 100 –

Healthcare 100 Blog Search: You can now search for specific blogs in the Healthcare 100 and quickly find their Healthcare 100 stats.

Healthcare 100 Blog Content Search: You can now search the content of blogs listed in the Healthcare 100. Want to see who’s been writing about a specific topic? Here’s an easy way to find out. We’ve created an index based on the content from Healthcare 100 blogs, which is updated throughout the week.

Recent Posts Popup: An icon of a plus sign is listed with each Healthcare 100 blog, which allows you to view a popup window displaying recent posts from that blog.

OPML Feed: This includes all feeds in the Healthcare 100.

Customized Healthcare 100 Badge: We’ve added a new JavaScript badge, customized for your blog, that you can easily add to your site. Just find your blog in the list and click on the badge icon to grab it.

FINALLY, there is one feature we’ve added that we really need your help with.

Like Todd’s Power 150, we’ve now included a flag icon to display each blog’s home country. You can add your country when you submit your blog for inclusion in the list. However, for blogs already in the Healthcare 100, we’re going through manually to make sure we’ve got the right flag — which is kind of a pain.

You can help us by finding your blog on the list and telling us if we have the right flag. If we don’t, please leave a comment here or , and we’ll get your new flag flying right away!

OK, I guess that’s it. We welcome your feedback and — just as we have with this new iteration of the Healthcare 100 — we’ll continue to respond to it.

One last point. As you explore the list, some of you will find that your rankings have dropped, and others will find that your rankings have increased — by a lot, in some cases.

If, for example, you’re an older blog that has a whole lot of Bloglines subscribers, you might feel a little pain when you see your new ranking. We think we were overweighting Bloglines before, though, so this is only fair to others on the list. We’ve obviously dramatically increased the importance of individual inbound links through Yahoo and Technorati InLinks, and this has also had a big effect on some blogs’ rankings.

Please note that if — even factoring in the new metrics — your Healthcare 100 ranking doesn’t look right, there’s no need to panic. The main reason for fluctuations in blog rankings, particularly among the lower ranking blogs, is that we sometimes collect inaccurate data from one of our sources, or experience some other kind of technical glitch.

If your ranking still looks off next time you check it, contact us and we’ll look into it right away.

We hope you have fun with the Healthcare 100, v. 2.0!

(Update: We originally posted the new Healthcare 100 on Friday with each of the Technorati-based categories on a 1-30 scale. Those have been modified to 1-20 scales.)