Development Effort Estimation in Free/Open Source Software from Activity in Version Control Systems

TL;DR

This paper presents a simple effort estimation model for FOSS projects based on developer activity data, incorporating direct feedback to distinguish full-time from part-time contributors, aiding resource planning.

Contribution

It introduces a novel effort estimation approach tailored for FOSS projects, utilizing developer effort profiles and feedback to improve accuracy.

Findings

Identified commit thresholds separating full-time and part-time developers.

Collected over 1,000 developer questionnaires for model calibration.

Provided guidelines and a tool for applying the model to FOSS projects.

Abstract

Effort estimation models are a fundamental tool in software management, and used as a forecast for resources, constraints and costs associated to software development. For Free/Open Source Software (FOSS) projects, effort estimation is especially complex: professional developers 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 simple effort 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 extracting the personal development profiles of several thousands of developers from 6 large FOSS projects, we asked them to fill in a questionnaire to determine if they should be considered as 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.%, and that minimizes the type I and type II errors. We finally offer guidelines and a tool to apply our model to FOSS projects that use a version control system.