Back-to-front programming effort prediction

This paper considers metrics for estimating software development effort. We are attempting to develop a family of metrics that will explain effort after the completion of a project and predict remaining effort when applied at some milestone prior to completion. We suggest that a milestone is meaningful only if it is early enough so that effort prediction is worthwhile and only if it is clearly identifiable. We analyzed the construction process for twenty-seven Fortran programs. The total programming time for each program was divided into two components, the design/coding time and the debug time. We chose the FCC (first clean compiled, i.e. first syntax-error-free) version as a meaningful milestone. In our data we found that the actual effort spent before this milestone was about 70% of the total effort, with 30% remaining thereafter. Furthermore, our results suggest that if an effort model performs well in estimating total programming effort at the end of development, it will also perform well at milestone FCC. But, the metrics we examined were not very useful in predicting the amount of effort remaining after the FCC milestone-even though each predicted total effort accurately enough. More work must be done order to find or create such an estimator.