Five Survival Techniques for Creating Usable Products
http://www.uie.com/articles/product_survival_techniques/

Perfetti, Christine
User Interface Engineering
2007

Abstract:

When we ask designers what stage they spend the bulk of their time in when launching a product, the majority of designers answer, the Implementation Stage. However, our research shows that the teams launching the most usable products on schedule and on budget spend the bulk of their time in the Measure and Learn stage.