Usability and downpour

There's an article on about "Developing a Basic Numerical Metric for Web Usability". It does make sense, but I'm not sure if it can be done. I think usability is more than the sum of a set of rules. Or atleast, it should be. Anyhow, the heavens have opened and what promised to become a sunny day has turned into a rainfest. Shame. And ofcourse I didn't bring my umbrella. Sigh.