Nearly all of us blog without any prospect of making money - either through advertising (adsense, referrals programs or similar) or sale of our blog.

For the vast majority of bloggers, it doesn't even have "knock-on" effects like promoting one's business or job prospects.

So why do we do it? Answer that question and you're on your way to defining your own performance metric.

I suspect that, if we're honest, it's about getting attention. We want our thoughts, views, experiences and opinions to count. We want to engage with like-minded people. Or - even better - convert opposite-minded people. (Some people like to have their views validated; others like to have them challenged.)

From this perspective, the most suitable metrics are those that try to capture the notion of "mindshare" - subscriptions/circulation, exposures/pageviews, reach, search engine rankings, citations, inbound links, mail-tos etc. These are hard to capture and integrate into a single metric, especially since they should take into account reputational scores.

Alternatively, your motivation may well be financial. There's a slew of "what's my blog worth?" sites, services and discussion out there. These seem to be based on estimated market rates for future earnings, and hence focus on what's called the "WTP" price (Willing-to-Pay price).

The flip-side is the "WTA" price (Willing-to-Accept price). This is the price a blogger is prepared to accept to sell his/her blog. Very few bloggers have answered this question: How much would you need to be paid in order to shut down your blog? (Personally, I put it at AU$1000.)

This is a useful question to ask yourself because it frames the valuation question in terms of compensation. There's a wealth of economic and psychological research to suggest that, generally, WTA>WTP (we value things more highly if we already have them). This is known as the Endowment Effect.

Right now, you're probably thinking "All those hundreds of hours of template hacking just to get it to align the sidebar properly ... surely I couldn't just abandon that for dirty, nasty cash!"

Which leads to the final class of performance metrics - accumulated effort. How many hours have you spent (wasted?) on your blog? For some bloggers, it's their primary hobby so the value of the blog to them is a function of how much spare time it soaks up. Half an hour a month is crappy hobby. So is fifty hours a week.

So, here's a few different questions to ask yourself about blog value:

* How many people did I persuade?
* How much would I accept to stop blogging?
* How many hours have I wasted on this thing?

-Greg.