As mobile applications become more pervasive, the need for assessing their quality, particularly in terms of efficiency (i.e. performance and resource utilisation), increases. Although there is a rich body of research and practice in developing metrics for traditional software, there has been little study on how these relate to mobile context-aware applications. Therefore, this paper defines and empirically evaluates metrics to capture software, resource utilisation and performance attributes, for the purpose of modelling their impact in context-aware mobile applications. To begin, a critical analysis of the problem domain identifies a number of specific software, resource utilisation and performance attributes. For each attribute, a concrete metric and technique of measurement is defined. A series of hypotheses are then proposed, and tested empirically using linear correlation analysis. The results support the hypotheses thus demonstrating the impact of software code attributes on th...