From the Script: SLIDE 31 - Program Errors

Errors tend to be made early in a project, and discovered late in a project.

These charts indicate that the number of errors introduced into a system decrease over the software development lifecycle . Most errors are introduced during the requirements definition phase - and fewer are introduced in later phases.

The cost to correct those errors, on the other hand, increase significantly over the lifecycle. The most expensive to correct are those that must be fixed during deployment, what is normally referred to as the "maintenance" phase.

When errors can be found early, the cost savings are substantial. This provides us with another criteria for evaluating languages. Those that eliminate errors early in development should tend to be more cost effective than those that do not.