Extreme Discount Usability Engineering Paul F. Marty College of Information Florida State University Tallahassee FL 32306-2100 Michael B. Twidale Graduate School of Library and Information Science University of Illinois at Urbana-Champaign Champaign, IL 61820 Abstract This paper explores the circumstances under which extremely discounted usability engineering techniques produce results that are worthwhile to researchers and practitioners. We present a method for usability analysis where an entire evaluation can be conducted in only thirty minutes, an amount of time we suggest as perhaps the smallest possible unit of analysis (or quantum) for complete usability evaluations. Based on a quantitative and qualitative analysis of thirty-six separate trials of this method, we assess the value of discount usability engineering at extremes of time and tests, and present our observations about the nature of user testing when pushed to extreme limits, a phenomenon we call the “Quantum Usability Effect.” Keywords Usability Analysis; User Testing; Discount Usability Engineering; Research Methods; Experimental Design;