A model for estimating program size and its evaluation

Estimation of the size and time required for software development is probably the most difficult aspect of any project. Up to now, most estimates have been done subjectively by experts. These estimates are often inaccurate. In the midst of development, faulty estimates may contribute to delays and/or excess expenses.In the last several years, several estimation have been proposed, most of which were models to estimate software development cost {manpower). These models used program size as a variable. However at the beginning of development, when estimations are made, program sizes are usually uncertain and costs (manpower) are equally uncertain.The authors developed a program-size estimation model for batch programs in a banking system, and used the model in an actual project. Using the adapted model, estimation errors amounted to only 7 percent. This is much better than the accuracy of estimtions made by experts in the field (usually about 10 percent accuracy), and indicates that objective estimation methods can be derived for program-size.In this paper, we introduce our estimation model and discuss the adaptation of that model for a specific project.