Högskolan i Skövde

Effort estimation models are a fundamental tool in software management, and used as a fore-cast for resources, constraints and costs associated to software development. For Free/OpenSource Software (FOSS) projects, effort estimation is especially complex: professionaldevelopers work alongside occasional, volunteer developers, so the overall effort (in person-months) becomes non-trivial to determine. The objective of this work it to develop a simpleeffort estimation model for FOSS projects, based on the historic data of developers’ effort.The model is fed with direct developer feedback to ensure its accuracy. After extractingthe personal development profiles of several thousands of developers from 6 large FOSSprojects, we asked them to fill in a questionnaire to determine if they should be consideredas full-time developers in the project that they work in. Their feedback was used to fine-tune the value of an effort threshold, above which developers can be considered as full-time.With the help of the over 1,000 questionnaires received, we were able to determine, for every project in our sample, the threshold of commits that separates full-time from non-full-time developers. We finally offer guidelines and a tool to apply our model to FOSS projects that use a version control system.