Cost of Issues
The lowest cost issue is the one never coded – this is why we have coding guidelines and best practises. The next lowest cost issue is the one found by the software developer who writes code and unit-test side by side. When coding the unit-test, the software developer has all the information available, what and why the code goes wrong. The test engineer doesn’t lose time on lengthy debugging and re-familiarizing himself with the code.
When validating firmware this graph shows that the number of issues “x” axis is proportional to the amount of time spent “y-axis. i.e. the less time evaluating the firmware will give you more issues and a high cost. If you increase your time spent on validation you will incur little cost and very few issues.