Software Effort Prediction using Regression Rule Extraction from Neural Networks

Neural networks are often selected as tool for software effort prediction because of their capability to approximate any continuous function with arbitrary accuracy. A major drawback of neural networks is the complex mapping between inputs and output, which is not easily understood by a user. This paper describes a rule extraction technique that derives a set of comprehensible IF-THEN rules from a trained neural network applied to the domain of software effort prediction. The suitability of this technique is tested on the ISBSG R11 data set by a comparison with linear regression, radial basis function networks, and CART. It is found that the most accurate results are obtained by CART, though the large number of rules limits comprehensibility. Considering comprehensible models only, the concise set of extracted rules outperform the pruned CART tree, making neural network rule extraction the most suitable technique for software effort prediction when comprehensibility is important.