 good thing. However, in a technology-driven industry, 'listening to your customer' is probably the worst thing you can possibly do. Understanding your customer is, however, completely crucial. 'Understanding' in this context implies a quantitative under- standing of the economic and emotional value of each of the domains and the perceived quality metrics of each domain. 21.15 Quantifying Domain-Specific Economic and Emotional Value Such an approach is not particularly difficult and can be objectively based. For example, it is possible to quantify the economic and emotional value of wide-area radio system mobility and ubiquity and build models of how the value/cost metric changes as bandwidth and perceived quality increases over time. It is possible to quantify audio system value on the basis of voice and audio value using well- defined and calibrated mean opinion score methodologies and to model how the value/cost metric changes as bandwidth and perceived quality increases over time. It is possible to quantify micro- and macropositioning value and to model how the value/cost metric changes as accuracy and fix speed increases over time. It is possible to quantify imaging system value and to model how the value/cost metric changes as resolution and colour depth and perceived quality increase over time using well- defined and calibrated mean opinion score methodologies. It is possible to quantify data system value both in terms of personal efficiency and corporate efficiency metrics. It might be argued that emotional value is hard to quantify. However, emo- tional value is part of the 'engagement cycle' that determines the 'soft value' (or 'fondness') that users feel towards particular service offerings. Intuitively, as emotional value increases, session length increases; a directly measurable metric. Making Telecoms Work Is domain value relevant to user-equipment design? Yes. We have chosen silicon value as an example but it is equally applicable to handset research and design. It is a valid approach to developing