On the Effect of Code Quality on Agile Effort Estimations: The Case of Shell

Abstract

Agile software development has interested researchers for the last decade. Agile software development teams develop iteration sessions that often last weeks. During development, teams work on technical code and its content. Intuitively, more effort is required to implement new features in poorly constructed code with low quality. This study investigates if and how developers consider the quality of their code during their agile effort estimations. Furthermore, we investigate whether the accuracy of their estimations could increase if developers considered the quality of the code. This study is conducted in a large software development department, that is part of Royal Dutch Shell. We take a mixed method approach, where we interview nine developers and quality experts and mine the repositories of six agile development teams. Initially, we reviewed the existing importance measures of code quality during effort estimations, including how code quality is maintained. We also evaluate the impact of code quality on estimation accuracy.

Developers did not consider code quality high on the priority list during the estimation stage of development. Similarly, we did not find an empirical relationship between the quality metrics and effort estimations. Surprisingly, code quality only had minor effects on the accuracy of the effort estimations. Developers did often encounter quality issues in legacy code. However, overall our study shows that code quality is only of minor importance during agile effort estimations.