What s Next After Counting Function Points?

What's Next After Counting Function Points?

The function point count for the requirements activity for the project is simply the aggregation of the counts for all the business use cases and the stored data. Now you must convert it to some indication of effort neededfor the requirements activity. Earlier in this appendix, we introduced a ruleof thumb used by Capers Jones. So many people use this rule that we believe it is worth trying on your project. Of course, data that comes from yourown organization is preferable, but to get that data you have to count the function points for previous projects so that you come up with your own metric of hours (or money) needed per function point.

You can also get help. This appendix concludes by suggesting some resources that have useful information. As we said at the beginning, our aim is to give you a gentle introduction to counting function points, and to intrigue you enough to want to investigate the subject further.

A great deal of material is available on the Web, much of it for free. The following organizations are good places to start when you are looking for more information on function points as well as productivity metrics:

• The David Consulting Group (www.davidconsultinggroup.com)

• The Gartner Group (www.gartner.com)

• International Software Benchmarking Group (www.isbsg.org.au)

• International Function Point Users Group (www.ifpug.org)

• META Group (www.metagroup.com)

• Quality Plus Technologies (www.qualityplustech.com)

• Software Productivity Research (www.spr.com)

• United Kingdom Software Metrics Association (www.uksma.co.uk/)

Additionally, we recommend these resources:

Dekkers, Carol. Demystifying Function Points: Clarifying Common Terminology. www.qualityplustech.com

This resource is used internally at IBM as one of its definition standards.

Dekkers, Carol. Function Point Counting and CFPS Study Guides Volumes 1, 2, and 3. Quality Plus, 2002. www.qualityplustech.com In addition to case studies, these study guides providelogistics and hints for the IFPUG Certified Function Point Specialist (CFPS) exam.

Fenton, Norman, and Shari Lawrence Pfleeger. Software Metrics: A Rigorous and Practical Approach (second edition). Thomson Computer Press, 1996. This book describes several ways of measuring the software development process. The case studies by themselvesfocusing on Hewlett-Packard, IBM, and the U.S. Department of Defenseare worth the price of the book.

Garmus, David, and David Herron. Function Point Analysis: Measurement Practices for Successful Software Projects. Addison-Wesley, 2001. This book provides a thorough treatment of function point counting using the IFPUG rules.

International Function Point Users Group. IT Measurement: Practical Advice from the Experts. Addison-Wesley, 2002.

Pfleeger, Shari Lawrence. Software Engineering: Theory and Practice(second edition). Prentice Hall, 2001.

As the title suggests, this book is a more general text on software. However, the discussions of measurement are relevant to this chapter.

Putman, Lawrence, and Ware Myers. Five Core Metrics: The Intelligence Behind Successful Software Management.Dorset House, 2003.

Not function points, but some other very good ways and things to measure. The authors demonstrate how the five core metricstime, effort, size, reliability, and process productivityare used to control and adjust projects.

There's more to function point counting, of course, but our discussion hereshould suffice for the quick counts needed at requirements time.