Affect in cost when remove phases

Question

How does the defect affect a cost if we remove them in later phases rather than initial phase?

Answer 1

If a defect is recognized at the early phase then it must be removed during that phase itself rather than removing them in some later stage. It is a fact that if a defect is postponed for later stage it proves more costly. A defect if recognized and removed during the early stage like requirement and design stage it will be more cost effective, whereas a defect removed at the time of maintenance is 20 times costlier than if we removed the defects in the requirement and design phases. For example, if a defect is recognized during requirement and design phase we only require to modify the documentation, but if recognized at the time of maintenance stage we not only need to remove the defect, although we also have to alter our test plans, perform regression testing, and modify all documentations. That is why a defect must be recognized /removed in former stages. The testing department must be involved right from the requirement stage and not after the execution stage.