Introduction

In Software Engineering Economics, Boehm presented the classic cost curve shown in Figure 18.1. As we progress from analysis to design, coding, testing, and production, the cost of fixing a problem rises. Note that the sharpest rise occurs when the system is released and distributed to its customers.

Figure 18.1. The "cost of fixing errors" curve

In Extreme Programming Explained, Kent Beck argues that this curve no longer represents the current state of software engineering. Instead, this curve is said to be flat. Two remarks can be made.

• Originally, this curve represented the cost of fixing errors introduced in earlier phases of a project. Kent Beck presents the curve as the "cost of change" curve.

• In his online article "Reexamining the Cost of Change Curve," Alistair Cockburn demonstrates that the cost of fixing errors still rises rapidly as the project progresses [Cockburn2000].