Open Journal Systems

Estimation of Testing and Rework Efforts for Software Development Projects

Mridul Bhardwaj, Ajay Rana

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In the planning of a software development project, a major challenge faced by project managers is to predict the rework effort. (Rework effort is the effort required to fix the software defects identified during system testing). The project manager’s objective is to deliver the software within the time, cost and quality requirements given by the client. To ensure the quality of the software, many testing cycles will be conducted before it is finally delivered to the client for acceptance. Each testing cycle is a costly affair as it involves running all possible test scenarios in all possible environments, followed by defect fixing and re-verification of defects. On average, two to three testing cycles are conducted but this depends on the number of defects identified during testing. The number of defects will depend on the team expertise and whether they earlier worked on similar projects and technologies. Therefore, it becomes critical to predict the number of defects that will be identified during testing and it is a very challenging task as it requires a good model to predict the rework effort.

In this paper, we describe the relationship among software size, number of software defects, productivity and efforts for software development projects. This relationship is established by using the multiple linear regression technique on the benchmarking data published by International Software Benchmarking Standard Group. There are 2 linear regression equation established one for web-based project and other for non-web-based projects. Results suggest that the web based projects are delivered faster, however, in web-based projects if we assume higher productivity higher number of defects will be found. Lower productivity will lead to fewer defects found and hence less testing and rework effort will be required therefor if we spend more development time to develop unit size than total number of defects will get reduced and will directly contribute in reducing the rework efforts. For non-web-based projects, results suggest that lower productivity will led to the more number of defects so non-web based project should be planned with much experience resources (higher productivity) so that we should have less defect and rework. Executing non-web based project with experience team require less time for development and most of the defect can be identified during unit testing and this will directly contribute in reducing the rework efforts. We infer from the relationship that software size has much significant impact on total number of defect in comparison to efforts. We also infer that while planning the software project we should use appropriate tools to reduce the margin of error in size estimation and we should also re-estimate the size, after every phase of the development life cycle to re-calibrate overall efforts and to minimize the impact on the project plan.

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