What is the Cost of Defects in Software Testing?

The expression “prevention is better than cure” is applicable to defects in the software development life cycle, in a manner that mirrors the medical field’s approach to illness.

The cost of finding and fixing mistakes in software goes up a lot as the software development process goes on. It can be costly and risky to fix bugs that are discovered after the software has been released, especially if they are discovered after the software has been released.  Modifying the code to fix a glitch can have a negative impact on the applications’ functionality, which may require further modifications, thereby escalating the expense, duration, and effort involved.

The Systems Sciences Institute at IBM estimates that the cost of correcting a glitch discovered during implementation is six times greater than the cost of identifying it during development. Fixing an error discovered after a product’s launch costs four to five times more than one discovered during design, and up to 100 times more than one identified during the upkeep phase. The cost of a bug goes up as the software goes through the SDLC.


Why do costs continue to increase throughout each stage of development?

It’s easier for developers to find problems in their code when they’re working on it because the code is still fresh in their minds, and it’s easier to fix even complicated issues. As time goes by and the code gets more complicated, it becomes harder for developers to remember all the details and find problems before they happen. A system like continuous quality integration can help developers find issues in the code while they are still writing it. This will make it easier for them to make the necessary changes.

During testing, it can take a long time to make mistakes on a developer’s local env. It’s easy to find issues that are clearly broken or don’t meet requirements, but it’s harder to find deeper defects, like memory leaks or race conditions. If these types of issues are not detected earlier in the coding phase, they often do not become apparent until the software is in the production phase.

It is difficult to find defects when software has been released and is being used in the field, and it is also risky to try to fix them. In addition to avoiding problems for real users, it’s important to make sure the service is always available for businesses. Due to the additional challenges and risks involved, the cost of fixing defects at this stage can be 30 times higher than if they were addressed earlier in the development process.

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Managing Defects

The most effective approach to managing defects is through the implementation of Defect Prevention and Defect Detection. This is essential for preventing huge costs and delivering a quality end product— quickly.

The process of defect prevention is a quality assurance procedure wherein testers thoroughly examine and scrutinize requirement specification documents, identify any potential ambiguities, and involve stakeholders early on to address any uncertainties. The document is subsequently updated, thereby preventing the introduction of defects into the product at an early stage. However, it is imperative to note that not all defects can be detected in advance, and a significant number of defects may be introduced during the development process as well. As a result, ongoing defect detection at each stage, with a particular focus on areas with high probabilities, is equally significant. 

To accomplish this, testers are required to execute both scripted test cases and exploratory tests. Exploratory tests are good for checking if something is working well or not. They provide a broader scope for debugging and exception handling, and are comprehensive, detail-oriented, and user-focused. The power, time-saving potential, and precision of automated testing tools cannot be questioned; hence, an ideal approach to track defects should involve a combination of both. It is possible to keep a track of the reported software bugs in software development projects using open-source bug tracking systems like Bugzilla.

Additionally, the developers should initially focus on the important defects worth fixing, rather than falling for the numbers. Defect severity and defect priority must be taken into account. Finally, after the developer fixes the problems, the tester should test the problem again. It is necessary to verify the defect in later releases to check if the expected behavior is being achieved, and the defect has been completely fixed once an open bug is closed. It is worth the effort considering the costs and implications of a buggy end-product, even though some level of duplicity of work, time and resources is required to handle these defects. 

Regardless, the key takeaway is to prevent most defects from occurring in the first place. Code review and root because analysis are essential.


It is human to err, but the costs of these errors must be considered and contained. A lot of time, effort and money can be saved by doing rigorous testing at all points in the software development lifecycle.

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