A study on estimating function point count of domestic software development

Function point model is the international standard method to measure the software size which is one of the most important factors to determine the software development cost. Function point model can successfully be applied only when the detailed specification of users' requirements is available in the domestic public sector, however, the budgeting for software projects is carried out before the requirements of softwares are specified in detail. Therefore, an efficient function point estimation method is required to apply function point model at the early stage of software development projects. The purpose of this paper is to compare various function point estimation methods and analyse their accuracies in domestic software projects. We consider four methods: NESMA model, ISBSG model, the simplified function point and the backfiring method. The methods are applied to about one hundred of domestic projects, and their estimation errors are compared. The results can be used as a criterion to select an adequate estimation model for function point counts.