There were only 2 bugs in production and end user finds the 38 bugs 🙂 because
- Requirement were not properly understood
- There were design/coding problems
- Some issues were left out during unit testing
- QA could cover all test scenarios
- Finally we delivered the product to user with 38 bugs
Relative Cost of fixing a bug
There were only 2 bugs during production, as graph line shows sum of 38, bugs were added up during all phases and becomes 38.
If we reduce the changes of bugs entered from one phase to another then only we will be able to fix only 2 bugs, otherwise need to fix all 38 bugs in our example.