Effort Estimation in Large-Scale Software Development : An Industrial Case Study

Context: Software projects frequently incur schedule and budget overruns. Planning and estimation are particularlychallenging in large and globally distributed projects. While software engineering researchers have beeninvestigating effort estimation for many years to help practitioners to improve their estimation processes, there is littleresearch about effort estimation in large-scale distributed agile projects.Objective: The main objective of this paper is three-fold: i) to identify how effort estimation is carried out in largescaledistributed agile projects; ii) to analyze the accuracy of the effort estimation processes in large-scale distributedagile projects; and iii) to identify the factors that impact the accuracy of effort estimates in large-scale distributed agileprojects.Method: We performed an exploratory longitudinal case study. The data collection was operationalized througharchival research and semi-structured interviews.Results: The main findings of this study are: 1) underestimation is the dominant trend in the studied case, 2) reestimationat the analysis stage improves the accuracy of the effort estimates, 3) requirements with large size/scopeincur larger effort overruns, 4) immature teams incur larger effort overruns, 5) requirements developed in multi-sitesettings incur larger effort overruns as compared to requirements developed in a collocated setting, and 6) requirementspriorities impact the accuracy of the effort estimates.Conclusion: Effort estimation is carried out at quotation and analysis stages in the studied case. It is a challengingtask involving coordination amongst many different stakeholders. Furthermore, lack of details and changes in requirements,immaturity of the newly on-boarded teams and the challenges associated with the large-scale add complexitiesin the effort estimation process