M. Kurosu (Ed.): Human Centered Design, HCII 2009, LNCS 5619, pp. 55–64, 2009. © Springer-Verlag Berlin Heidelberg 2009 Usability Evaluation of Mp3/CD Players: A Multi-Criteria Decision Making Approach Ergün Eraslan Department of Industrial Engineering, Baskent University, 06590 Ankara, Turkey eraslan@baskent.edu.tr Abstract. Globalization and the competition obliged the user-oriented design today. In the last years, usability has become a highly important research sub- ject. Usability, considering user satisfaction along with the user performance, is one of the key factors in determining the success of a product in today’s com- petitive market. Product usability is a prerequisite for high customer satisfaction and future sales of companies. Mp3 players and portable CD players are se- lected for this study since usability is highly important for them. Designing a usable mp3 or CD player is extremely important for users who have close inter- action with them. In this study, 14 different mp3/CD players are selected and their usability is analyzed. The usability criteria used in the mp3/CD players’ evaluation are divided into two major categories: performance and emotional expectations. The best alternative is determined with three different multi- criteria decision making methods which are TOPSIS, Analytic Hierarchy Proc- ess (AHP), and Fuzzy Axiomatic Design Theory (FADT). Although the same data obtained from semantic differential experiment are used for all multi- criteria decision making methods, different rankings are obtained from each method. Keywords: Usability, TOPSIS, Analytic Hierarchy Process (AHP), Fuzzy Axiomatic Design Theory (FADT), Semantic Differential Scale. 1 Introduction User-oriented manufacturing and design became a must because of the competition among the firms. Customer profile has significantly changed. Customers who can buy every product have disappeared. Instead, customers know what they want and choose the products which satisfy their senses and needs in terms of price and design. Consum- ers want to buy “usable” products which will satisfy their needs and be easy to use. Usability of a product is a very valuable prerequisite for future sales and high cus- tomer satisfaction. Understanding the product features which are significant for the customers and reflecting the feedbacks of the customers to the design and develop- ment processes of the product are important. Designers have to evaluate vital points of usability and the satisfaction and delight rose by these vital points carefully. Usability concept includes a few concepts such as effectiveness, efficiency, and user satisfaction. In its broadest sense, usability is the expression of whether the