Step-by-step guide on how to measure Defect Escape Rate

Helpful summary

Overview: In this article, we offer a step-by-step guide on measuring Defect Escape Rate (DER), emphasizing its importance for software quality assurance and customer satisfaction.

Why you can trust us: Instatus provides straightforward solutions for clear communication of issues,  such as beautiful status pages and comprehensive website monitoring tools, underlining our commitment to transparency and trust. 

Why this is important: Understanding DER is essential for identifying weaknesses in testing processes and enhancing product reliability.

Action Points: We recommend implementing a systematic approach to track, categorize, and regularly calculate DER for continuous improvement.

Further Research: Explore tools like Instatus for effective communication when defects occur to maintain user trust and high software quality.

Need help measuring your defect escape rate?

Imagine releasing a new software update with confidence, only to discover that customers are encountering issues you thought were resolved. It happens more often than you'd think. That's where the Defect Escape Rate (DER) is crucial, a metric that tells you how many issues have slipped through the cracks and made it through the official release.

Instatus understands your need to monitor and reduce escaped defects. Our platform helps keep your customers informed of any ongoing issues using a beautiful status page that brings transparency to the forefront.

In this article, we'll explore how to measure the DER effectively, ensuring that your releases are as smooth as the status pages Instatus helps you create.

Why listen to us?

Understanding and minimizing the Defect Escape Rate (DER) is vital for software quality. At Instatus, we help companies set up status pages to inform users of any issues, including defects that persist after QA. 

For example, SaaS companies like Railway, a CRM tool, use Instatus to help communicate issues to their users. Here is what their status page looks when they don’t have any issues:

What is defect escape rate (DER)?

The Defect Escape Rate (DER) is a DevOps metric used to evaluate the effectiveness of a software team's quality assurance process. It calculates the proportion of defects that were not caught during testing and only became apparent after the product was released. 

Put simply, DER gives you a numerical value that represents the number of bugs that end users encounter after launch compared to the total number of bugs identified throughout the development cycle. That is to say, before and after QA and launch.


To break it down: if your testing team identifies and fixes 80 bugs before release, but your customers find 20 more bugs after the product goes live, bringing the total to 100 bugs found. Therefore, your DER is 20%.

This number is significant because it helps you understand the robustness of your testing process and where it may need improvement. Monitoring and minimizing the DER is essential to ensuring that your software is as reliable and user-friendly as possible, much like how our status pages at Instatus aim to be for our users.

Defect escape rate calculation example

Let’s consider another example to make the picture crystal clear.

Imagine a scenario where your team found 100 defects during testing, but after deployment, customers reported an additional 10 defects. Here, the DER would be calculated as: 

(10 escaped defects) / (100 detected defects + 10 escaped defects) = 9%.

Why do you need to measure defect escape rate?

Improve product quality

By measuring DER, you can identify the specific areas where bugs are slipping past your quality checks. This insight allows you to focus your efforts on tightening up those weak spots, whether that means adjusting your testing strategies, adding more test cases, or reevaluating your development practices. The goal is to catch more bugs before they reach your users.

Enhance customer satisfaction

Customers expect the software they use to work smoothly. A high DER means more bugs are likely to annoy your users, potentially driving them to your competitors. By keeping your DER low, you ensure that users experience fewer problems, resulting in higher satisfaction rates. Happy customers are more likely to stick around and recommend your product to others which helps you with both retention and growth.

Increase development efficiency

A lower DER not only signifies better product quality but also reflects a more efficient CI/CD process. When you're regularly identifying and addressing the root causes of defects that escape into production, you're effectively reducing the number of bugs that need to be fixed after release. This proactive approach saves time and resources. Fixing bugs in production is often more costly and time-consuming than resolving them earlier in the development cycle. 

Over time, a focus on reducing your DER can lead to a smoother DevOps implementation workflow and a more predictable release schedule.

Foster continuous improvement

Regularly measuring and analyzing the DER encourages a culture of continuous improvement within your organization. It pushes teams to reflect on their practices, learn from each release, and persistently look for ways to enhance their workflows and project management

If you want to keep up with customers' increasing expectations for software quality and reliability, you can’t ever stop improving.

Mitigate financial risks & manage your reputation

Lastly, tracking DER helps mitigate financial risks associated with post-release defects. Bugs that escape to production can lead to costly hotfixes, customer support overhead, and even legal issues if data breaches or significant downtime occur. 

A lower DER is not just a measure of software quality but also an indicator of lower financial exposure and better risk management. This makes monitoring your DER critical to maintaining your reputation among customers and potential investors.

Our 6 steps to using DER to improve software quality

Step 1: Track all defects

To make informed decisions about your software quality, you need comprehensive data. Begin by setting up a system that captures every defect discovered during development, testing, and after release. Whether you choose a sophisticated website monitoring tool, a bug-tracking software, or start with a basic spreadsheet, the key is to ensure that no bug goes unrecorded. This complete record forms the foundation for calculating an accurate DER and ultimately improving your quality assurance process.

Step 2: Categorize defects

Defects can vary widely in their impact and nature. By categorizing each defect based on factors like severity, type (e.g., UI, functionality, performance), and origin (e.g., coding error, design flaw), you'll be able to perform a more granular analysis of your DER. This helps you pinpoint not just how many bugs escaped, but which types of bugs are most likely to slip through your testing process.

Step 3: Calculate DER regularly

Consistency is key when it comes to measurement. Calculate your DER at the end of every release cycle to track the effectiveness of your quality assurance over time. This regular calculation allows you to spot trends and measure the impact of any changes you make to your development or testing protocols.

Step 4: Analyze the results

With your DER calculated, take the time to analyze the results. Look for patterns in the data that may indicate systemic issues or recurring problems. Understanding the characteristics of defects that escape to production can inform targeted improvements in your software development lifecycle.

Step 5: Implement process improvements

Use the insights gained from your analysis to implement changes aimed at reducing your DER. This might involve training for developers, updates to testing procedures, or the introduction of new quality assurance tools. By addressing the root causes of defect escapes, you can enhance the overall quality of your software.

Step 6: Monitor changes

After you've implemented improvements, it's crucial to monitor their impact on future DER figures. Observe how the changes affect the number and severity of defects that make it to production. By keeping a close watch on these metrics, you can assess the effectiveness of your interventions and make further adjustments as needed. This ongoing vigilance ensures a continuous uplift in software quality and a more robust development process.

Best practices for measuring and reducing defect escape rate

To effectively measure and reduce the Defect Escape Rate (DER), it's essential to adopt a set of best practices. These practices are designed to streamline your processes, enhance the accuracy of your defect tracking, and ultimately deliver a higher-quality product. Here are some key practices to consider:

Establish clear criteria: Set specific definitions for what counts as a defect to keep everyone on the same page. This uniformity helps in accurate tracking and efficient defect management.

Communicate effectively: Keep clear communication lines within your team and with stakeholders. Use a tool like Instatus to communicate ongoing bug fixes and when systems will be operational. We understand that good communication is the key to making progress. That’s why we designed our status pages to be 10 times faster than traditional status pages. 

You can even use Instatus privately and publicly  on your own domains and customize the color and style to ensure that it fits with your brand. Have a look for yourself by creating a free status page.

Automate where possible: Leverage automation for tracking defects and calculating DER to increase efficiency and reduce errors. Automated systems ensure consistent and timely data collection.

Foster a quality culture: Build a team culture where quality is everyone's business. Encouraging proactive issue reporting and ownership of quality leads to more robust products.

Regularly review test coverage: Keep test cases current to match new features and changes. Regular updates help maintain comprehensive coverage and catch more defects pre-release.

Involve users in testing: Incorporate user feedback through beta testing phases. User insights can reveal issues that internal tests might miss.

Prioritize defect fixes: Address defects based on their severity and user impact. Prioritization helps manage risks and focuses efforts on the most pressing issues.

Conduct post-release monitoring: Watch for issues after launch to catch and fix defects early. Prompt responses to post-release defects can preserve user trust and satisfaction.

Wrapping up

Measuring and improving your Defect Escape Rate is an ongoing process. By following the steps we outlined in this article, you gain valuable insights into your software quality and how to improve it in the future. 

Instatus provides a seamless way to communicate with users when defects do escape, keeping transparency at the forefront and trust intact. Bugs are bound to come up from time to time, and when they do, let Instatus handle the status pages, and keep your users in the loop.

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