Development of a hybrid cost estimation model in an iterative manner

Cost estimation is a very crucial field for software developing companies. The acceptance of an estimation technique is highly dependent on estimation accuracy. Often, this accuracy is only determined after an initial application. Possible further steps for improving the underlying estimation model typically do not influence the decision on whether to discard the technique or deploy it. In addition, most estimation techniques do not explicitly support the evolution of the underlying estimation model in an iterative manner. This increases the risk of overlooking some important cost drivers or data inconsistencies. This paper presents an enhanced process for developing a CoBRA® cost estimation model by systematically including iterative analysis and feedback cycles, and its evaluation in a software development unit of Oki Electric Industry Co., Ltd., Japan. During the model improvement cycles, estimation accuracy was improved from an initial 120% down to 14%. In addition, lessons learned with the iterative development approach are described.