Estimating Software Project Effort Using Analogies

Estimating Software Project Effort Using Analogies

NOVEMBER 1997 | Martin Shepperd and Chris Schofield
The paper "Estimating Software Project Effort Using Analogies" by Martin Shepperd and Chris Schofield explores an alternative approach to software project effort estimation using analogies, a form of case-based reasoning (CBR). The authors argue that this method can complement traditional algorithmic models like COCOMO, which often have high error rates. The key idea is to characterize projects based on features such as the number of interfaces, development method, and size of functional requirements documents. Similar projects are identified by measuring their Euclidean distance in n-dimensional space, where each dimension represents a project feature. The known effort values of the nearest neighbors are then used to predict the effort for the new project. The process is automated using a PC-based tool called ANGEL. The paper compares the accuracy of analogy-based estimation with regression models on nine industrial datasets, totaling 275 projects. The results show that analogy-based estimation outperforms regression models in terms of both mean magnitude of relative error (MMRE) and Pred(25) (the percentage of predictions within 25% of the actual value). The authors also conduct a sensitivity analysis to assess the method's stability over time and its performance with different dataset sizes. They find that analogy-based estimation is more robust and can handle datasets with fewer projects, making it suitable for early-stage project estimation. The paper concludes that analogy-based estimation is a viable technique for software project effort prediction, offering advantages such as intuitiveness and the ability to handle poorly understood domains. However, it also acknowledges limitations, such as the need for a sufficient number of projects to ensure accurate predictions. The authors recommend that software development organizations consider using analogy-based estimation alongside other methods to enhance the accuracy and reliability of project cost estimates.The paper "Estimating Software Project Effort Using Analogies" by Martin Shepperd and Chris Schofield explores an alternative approach to software project effort estimation using analogies, a form of case-based reasoning (CBR). The authors argue that this method can complement traditional algorithmic models like COCOMO, which often have high error rates. The key idea is to characterize projects based on features such as the number of interfaces, development method, and size of functional requirements documents. Similar projects are identified by measuring their Euclidean distance in n-dimensional space, where each dimension represents a project feature. The known effort values of the nearest neighbors are then used to predict the effort for the new project. The process is automated using a PC-based tool called ANGEL. The paper compares the accuracy of analogy-based estimation with regression models on nine industrial datasets, totaling 275 projects. The results show that analogy-based estimation outperforms regression models in terms of both mean magnitude of relative error (MMRE) and Pred(25) (the percentage of predictions within 25% of the actual value). The authors also conduct a sensitivity analysis to assess the method's stability over time and its performance with different dataset sizes. They find that analogy-based estimation is more robust and can handle datasets with fewer projects, making it suitable for early-stage project estimation. The paper concludes that analogy-based estimation is a viable technique for software project effort prediction, offering advantages such as intuitiveness and the ability to handle poorly understood domains. However, it also acknowledges limitations, such as the need for a sufficient number of projects to ensure accurate predictions. The authors recommend that software development organizations consider using analogy-based estimation alongside other methods to enhance the accuracy and reliability of project cost estimates.
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