What impact does your blog have on your business web site?

This was a question recently addressed by a company with some degree of bias, but seems to have done a good job of analyzing the data for at least one of their clients. I don't think they have an axe to grind on the blog versus no blog decisions; rather, they sell tracking services.

The approach they used looks reasonable - you can read the details here. The suggestion that their blog readers are 22% more likely to sign up for their newsletter was interesting, but the average time spent on the site seems much more valueable to me -

"Even I was surprised by the results—people who read the blog spend about 60% more time on the site than people who didn't." -- ClickTracks Customer

This corresponds to something I've been saying for a long time - if you want to get a lot visitors, you probably should be concerned with the number of pages in the [primary] search index. Likewise, if you want to get prospects, you probably need to be concerned with the abount of time they spend looking at your content.