Let's face it, it's tough to get an accurate read of how your blog is performing by measuring just one metric. Case in point, let's look at how I've tracked traffic here since launching The Viral Garden in 2006.
For the first year of blogging here, I used SiteMeter to track the number of visitors to this blog. I noticed that while posts were gradually getting more comments and the blog was collecting more links, that daily traffic was barely growing. After a few months I was averaging about 100 visitors a day, but by February of last year, that number was only up to around 200 visitors a day.
So I started doing some snooping around my site's analytics, and discovered that while traffic was growing at barely a crawl, Feedburner told me that the number of subscribers to the blog's feed was growing about twice as fast, and had caught the avg. daily traffic. That opened my eyes, and I started paying attention to my subscribers, and how they were reading my feed. Based on the information I got from Feedburner, I changed my blog's layout and added options to sub to my blog's feed via the most popular feed readers, such as Google Reader, Netvibes, and NewsGator. Before I had only had a button for Bloglines, which was buried down toward the end of the sidebar. After adding more buttons (including a FB chicket counter), I moved them all to the top of the blog, where they could be easily found.
As you can see, these changes accelerated the growth I was seeing from feed subscribers, and while it has slowed a bit recently, the number of feed subscribers is still currently at record levels. And as subscribers continue to take off, daily traffic to the blog continued to barely grow, it was at around 200 visitors a day in February of 2007, and now it's at about 275 a day. A lot of this is simply a change in how people want to view blog content. Now, most want to keep up with their favorite blogs via a feed reader. That wasn't so much the case in 2006 when I launched The Viral Garden. This is why you need to look at multiple metrics to give you an idea of emerging patterns within your readership.
Another example, while growth of traffic to the blog and feed subscribers are currently at all-time highs, both are slowing in growth. But the number of email subscribers to my feed is taking off. I launched an email version of my feed via Feedburner in late April of last year. For much of last year and this year, I would add 5-10 new email subscribers a month. But over the past 2-3 months, I've been adding 20+ subscriptions a month, and it's on pace to catch avg. daily traffic to the blog around Feb or March of next year.
Why the sudden spike? My guess is it's partly because I've spoken at several confs over the last 3 months (where the attendees are newer to social media, and might prefer to have blog posts sent to them via email), and because my Twitter usage has spiked in the last few months, resulting in my adding several hundred followers. And my guess is that many of these followers are new to reading blogs as well, and are more interested in the email version of my feed.
The point in all this is, if you keep a close eye on your blog and track multiple metrics, you can get a much better idea of how your readers are interacting with your blog, and what appeals to them. Do you know how many comments per post you averaged last month? How your traffic/subscribers are trending? Do you know which site was the top referrer of traffic to your blog last month? You should.
Which metrics do you measure to determine if your blog is effective? Why do you choose those particular ones?
PS: As you might have guessed, I'm a big fan of Feedburner. Here's a post I wrote last year that walks you through 10 Ways You Can Use Feedburner To Grow Your Blog.