Validating the external quality subcharacteristics of software products according to ISO/IEC 9126 Ho-Won Jung ⁎ Korea University Business School, Anam-dong 5Ka, Sungbuk-gu, Seoul 136-701, South Korea Received 20 December 2006; accepted 11 March 2007 Available online 18 April 2007 Abstract The study statistically tests the proposition of the ISO/IEC 9126 standard that higher external quality (quality when software is executed) implies higher ‘quality in use’. For this purpose, the study based on 75 user survey data shows that individual external quality subcharacteristics are positively associated with user satisfaction as defined in ‘quality in use’. This study also investigates the external quality subcharacteristics that strongly influence user satisfaction. Our results provide guidance for the revision of the Standard as well as supporting management decisions (i.e., resource allocation) aimed at improving software product quality. © 2007 Elsevier B.V. All rights reserved. Keywords: ISO/IEC 9126; Marginal satisfaction; Ordered probit regression; Software quality characteristics; User satisfaction 1. Introduction The competitive environment in the software market and the needs of customers require that software developers focus on user satisfaction as a measure of software product quality. User satisfaction is often considered as the ultimate aim of quality management and has a positive impact on organizational cost, profit, and sales growth [27]. However, users are often dis- satisfied with software quality [20]. In fact, widespread dis- satisfaction in the United States led to recent legislation governing software quality and suppliers' responsibility [21]. Thus, understanding the key quality attributes that influence user satisfaction can lead to a competitive advantage in the software market place by aiding management decisions such as resource allocation, aimed at improving software product quality [22]. Investigation of the quality attributes that influence user satisfaction requires the use of a quality model. A quality model normally defines a set of quality attributes that may be present in software product. In particular, because users place different values on each attribute depending on the product's use, it is important that quality attributes are clear to the consumer. Software engineering researchers and practitioners have suggested many different quality models each with a varying number of attributes [2,11,29]. Recently, in order to address the issues of software product quality in a consistent way, ISO/IEC 9126 (Software Product Quality) [17] defined six character- istics, 27 subcharacteristics, and their associated measures of software product quality. A summarized explanation of quality models and their attributes can be found in [23]. The proposition of ISO/IEC 9126 is that higher external quality (quality when software is executed) indicates higher ‘quality in use’. Subcharacteristics of external quality are of little value by themselves unless there is empirical evidence that they are associated with important characteristics such as user satisfaction, defined in ‘quality in use’. The purpose of this study is to test the proposition by showing that each of the subcharacteristics of external quality is positively associated with user satisfaction, defined in ‘quality in use’. A univariate ordered probit regression [37] is applied to 75 user survey data based on the use of a query and reporting tool. Ordered probit regression is useful for analyzing datasets with a dependent variable of an ordered response scale of user satisfaction [15]. In addition, this study investigates the external Computer Standards & Interfaces 29 (2007) 653 – 661 www.elsevier.com/locate/csi ⁎ Tel.: +82 2 3290 1938; fax: +82 2 922 7220. E-mail address: hwjung@korea.ac.kr . 0920-5489/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.csi.2007.03.004