From Writing Documents to Meeting User Information Needs  

As professional Technical Communicators, we constantly struggle with the question 'Is what we produce being used and is it making a difference?' Too often, we base our measures of success on our own views of what makes a good document, Help system, or other information product. Through broader and more detailed analysis, and by measuring success based on how our information products affect others, we can increase the effectiveness of our information products and increase our value to our users and companies.

Hurst, Bob, Cindy Line and Kerry Newberry. STC Proceedings (2003). Articles>Writing>Usability>Assessment