2 nd Workshop in the workshop series on Empirical Software Engineering “The future of empirical studies in software engineering”, Monte Carzio Catone, Italy, Sept 29, 2003, pp 17-25. Cognitive Effort in Collective Software Design: Methodological Perspectives in Cognitive Ergonomics Françoise Détienne, Jean-Marie Burkhardt, Willemien Visser EIFFEL Research group - Cognition and Cooperation in Design, INRIA, Domaine de Voluceau, Rocquencourt, 78153 Le Chesnay, France {Francoise.Detienne, Jean-Marie.Burkhardt, Willemien.Visser} @inria.fr Abstract. Empirical software engineering is concerned with measuring, or estimating, both the effort put into the software process and the quality of its product. We defend the idea that measuring process effort and product quality and establishing a relation between the two cannot be performed without a model of cognitive and collective activities involved in software design, and without measurement of these activities. This is the object of our field, i.e. Cognitive Ergonomics of design. After a brief presentation of its theoretical and methodological foundations, we will discuss a cognitive approach to design activities and its potential to provide new directions in ESE. Then we will present and discuss an illustration of the methodological directions we have proposed for the analysis and measurement of cognitive activities in the context of collective software design. The two situations analysed are technical review meetings, and Request For Comments-like procedures in Open Source Software design. 1 Introduction Empirical software engineering (ESE) is concerned with measuring, or estimating, both the effort put into the software (SW) process and the quality of its product. Measurement related to the process reflects the cost (e.g., in person-hours) and is mainly related to the phases as defined in SW process models. Measurement related to the product reflects the SW quality with respect to norms (ISO) or criteria such as reliability, efficiency, usability, maintainability, and portability. A good balance is expected to be found between the effort put into the process and the quality of the final product. However, it is not clear how this effort and this quality are related. We defend the idea that measuring and relating process effort and product quality cannot be performed without a model of cognitive and collective activities involved in SW design, and without measurement of these activities. This is the object of our field, i.e. Cognitive Ergonomics of design. After a brief presentation of its theoretical and methodological foundations, we will discuss a cognitive approach to design activities and its potential to provide new directions in ESE. Then we will present and discuss an illustration of the methodological directions we proposed for the analysis and measurement of cognitive activities in the context of collective software design.