Communications of the ACM: This is a large PDF file. This articles reports on the potential ROI of an EPSS. The study used a prototype version of a performance support component of a customer service system. They authors calculate only the potential training cost savings based on a 50% (best-case), 30%(expected) and 20% reduction in training time. While novice users where much more successful with the EPSS prototype, the calculated reduction of training costs resulted in break points ranging from 1.1 to 18.2 years. This is a very useful article. It shows the ROI calculations and discusses the difficulty of measuring the other possible benefits of a performance support system. (2001-03-18)