How does CAST’s automated approach to counting function points compare with IFPUG’s manual approach?
As the table below shows, there’s very little difference. The CAST AIP follows the same process followed by IFPUG-certified counters except for the last step in the process. Because of this variation in the last step of the procedure, CAST-computed function points will vary from counts made by an IFPUG-certified professional. In detailed calibration studies done with function point experts David Consulting Group (DCG), we have found the difference between the IFPUG manual approach and the CAST automated approach is between ± 11%. For IFPUG manual counts the typical accepted certified practitioner variance is generally falls within ± 10%. However, variances can significantly exceed this range based on the availability and quality of supporting documentation, and subject matter experts. The CAST automated approach does not rely on any documentation or the knowledge of subject matter experts. When customers have their own in-house function point teams, we’ve seen function point experts re
