This appendix contains information about how the costs and benefits of agile and plan-driven methods can be and have been measured. Unfortunately, since agile methods are relatively recent developments, relatively little agile data is available.
Some of the information uses existing models, like COCOMO II, to infer how agile and plan-driven approaches work based on historical data. Others present experimental findings.
We hope that this collection of material will provide the basis for further work in quantifying the costs and benefits associated with software development practices: agile, plan-driven, and hybrid.
Figure E-1, from Kent Beck's Extreme Programming Explained ...