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The vitality of root cause analysis in software testing

Root Cause Analysis for Software Defects — the what, why, and how

November 23, 2022
Kazuaki MatsuoKazuaki Matsuo
Kazuaki Matsuo

Customers invariably look for excellent experiences offered by the software they use, which makes it unquestionably crucial for developers to support customer needs and build a great brand reputation. Quality being a primary attribute, developers must ensure the software is defect-proof and delivers the desired outcomes. 

Check out: How to Achieve B2B Customer Experience Success With 5G?

What are defects?

From the perspective of software development, a software defect refers to any deviation between the actual and expected result where the software works perfectly but doesn't meet the user expectation (or a deviation from the software requirements specification). ((Source: ISTQB)

Defects can be any error, fault, flaw, or failure in the computer program causing an unexpected or incorrect result. With applications' changing nature and dynamics, the range of software defects has become more extensive. 


What is root cause analysis?

Every issue has a root cause to it, and so does any software defect. Root cause analysis in software defect refers to the collective term that comprises multiple tools, techniques, processes, and approaches organizations utilize to identify the underlying cause of the software defect. This helps developers better understand why a particular issue crops up in the software and how the team can remediate the problem at its source.

Check out: 10 Ways to Accelerate the Software Testing Cycle

The importance of root cause analysis

When executed efficiently, a Root Cause Analysis helps pinpoint any non-conforming element and provides the required data to prevent the issues from re-occurring. When enterprises perform RCA, they not only determine the what, how, and why of the problem, but the right analysis also outlines required improvements that teams need to incorporate to ensure that problems do not recur.

Also check: Best Practices for Application Performance Testing

Some of the key benefits of RCA can be compiled as follows:

  • Cost reduction

Multiple studies indicate that the cost of fixing defects in applications increases significantly in the later stages of the development process. Defects identified in the implementation stages might cost around five times more than they would in the design stage. These evidently impact the development costs and might also result in loss of customer faith in case the defects are discovered after the app is launched in the market and can cost the brand its reputation. Effective RCA can help companies avoid detrimental financial losses and win client trust.

  • Accelerated time to market

Identifying the root causes of any defect at the initial stages of app development helps to implement corrective actions appropriately, and thereby, subsequent releases of the product require lesser time in testing. Therefore, the products reach the market sooner with fewer issues, and as a result, companies can reduce the time to market and gain a competitive advantage.

  • Improved software quality

By enabling companies to identify the source of defects, the problem-solving process becomes more seamless, ensuring superior software quality. RCA enables companies to identify the current as well as future needs for the overall improvement of the software and the entire organizational systems.

  • Enhanced customer satisfaction

Flawlessly performing software is the key to retaining its users. As RCA helps to reduce the number of defects exponentially, it helps ensure optimal user experiences. Moreover, with efficient RCA, the potential defects in future releases can be controlled effectively too, which proves to be beneficial to companies in quality-critical industries where the safety and reliability of the software are critical.

Read: Client-Side Performance Testing - Metrics to Consider

How to execute root cause analysis?

Determining the root causes of defects and resolving them is crucial to eliminate the chances of the occurrence of defects. For efficient root cause analysis, companies require a structural and logical approach. Following are some of the primary steps for the process of performing and documenting RCA.

1. Define defect or problem: 

Prior to executing RCA, a team needs to identify and define the problem accurately. This can include addressing questions like 

  • what exactly happened
  • the point in the process at which the problem occurred
  • how often it has happened, the pattern of occurrence, how the issue was detected, and so on. 

With all the information acquired, the team might look for further details to understand the problem better. The team must review the collected information and effectively define the problem based on the facts.

Also read: Saving Test Data to Make Debugging Easier

2. Collect data regarding defects:

It is imperative to precisely collect data regarding the defect that covers information on the impact, proof of defect, and how much time the defect existed if it's a recurring defect. Often it is essential that teams communicate with customers or employees. Before identifying the root cause, one must analyze the defect entirely and gather all the data and evidence.

3. Identify the root cause of the defect: 

Post collecting the data, the RCA team works toward identifying the primary cause of the defect. The team conducts a brainstorming session, focusing on the 'why' of the defect that occurred and accordingly identifying tools that best suit the requirements to lead to effective results.

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4. Deploying the right corrective action:

Root Cause Corrective Action (RCCA) involves fixing or resolving the issues by determining the suitable measures and actions to eliminate the defect. The key focus should lie on eliminating the root cause of the problem or defect to avoid future recurrences. 

It is vital for the team to identify the right tool for fixing the defects. Fixes provided by the support team are often temporary for the customer site where the issue is reported. As and when the fix is merged into an ongoing version, it is essential that the RCA team performs a proper impact analysis to ensure that no existing feature is broken. Further, an efficient workflow must be deployed to validate the fix and monitor the implemented solution to check if the solution is efficient. 

Test your apps on real devices and get accurate results. Know more.

5. Executing Root cause Preventive Action (RCPA):

Ongoing improvement and prevention of defects bring out the true value of root cause analysis. Determining the underlying cause of a problem, the RCA team offers recommendations that can pinpoint techniques to prevent similar issues in the same or other applications. RCA workflows are expected to deliver explicit guidance on how to prevent similar issues from re-occurring. These suggestions or root cause preventative actions involve diverse ongoing recommendations like improved documentation, netter team training or skill set enhancements, process changes, IT infrastructure improvements, and much more.

Test your mobile apps on thousands of real devices connected to carrier networks in locations around the globe. Learn more.

Leverage HeadSpin to identify root causes of performance and functional issues and deliver a flawless user experience 

HeadSpin offers a data science-driven testing platform that allows companies to test applications on real devices across multiple locations, capture key performance issues, identify the underlying causes, and improve overall app performance to ensure superior user experience. 

  • Capturing performance sessions and offering issue cards

HeadSpin's AI-driven connected experience insights capabilities enable companies to identify root causes behind performance issues and recommend fixes. 

The platform helps to:

  • Isolate issues and provide insights into the health of the apps, OS, device, and network
  • Create a waterfall of the UI flow
  • Automatically and proactively identify user experience and quality issues in the app
  • Identify the PI and CDN call which is responsible for the poor UX

The unique AI-enabled capability of the HeadSpin Platform allows you to capture performance sessions that help better understand app performance by easy issue identification and showcase issues through user-friendly issue cards.

What is an issue card?

Every issue card represents a problem in the app's network traffic with a particular host. The cards are segregated by time impact, and each of them corresponds with dots on the issue curve.

HeadSpin's session capture review works as follows:

Working of session capture
Working of session capture
Waterfall UI
Waterfall UI
HeadSpin session impact curve and performance issue cards
HeadSpin session impact curve and performance issue cards
  • Implementing Root Cause Analysis

By leveraging data science to identify issues and perform RCA in software, HeadSpin allows companies to make improvements to the applications built and delivered seamlessly. With the data acquired from device sessions, HeadSpin enables automatic error detection; it analyzes the root causes covering multiple layers of the stack, including QoE assessment of audio/video content, code and packet visibility, and much more.

Securely test audio and video quality including DRM content. Learn how.

The Root Cause Analysis is supported by the alignment of data on a common timeline.

With HeadSpin

  • Capture data streams across the tech stack
  • Surface issues in each data stream
  • Align data streams and issues on a common timeline
  • Prioritize issues based on the impact on to end user/client application
  • Begin with the highest priority user-facing issues and dive deeper into root causes within a specific timeframe


Software defects are almost unavoidable. Nonetheless, efficient RCA can help developers build flawless software products and deliver optimal experiences to customers. By enabling companies to identify the root causes of performance and functional issues of applications, HeadSpin makes it more seamless for software companies to ensure the high quality of the software and speed the time to market, leading to an overall enhancement of brand values and customer loyalty.


Q1. What are defects, bugs, and errors?

Ans: Any variation between the actual result and the expected result is known as a defect. If a developer identifies an issue and rectifies it himself in the development phase, then it refers to a defect.

When testers find a mismatch in the application/system in the testing phase, it refers to a Bug.

If a developer is unable to compile or run a program successfully, then they refer to it as an error.

Q2. What are the popular techniques of root cause analysis for software defects?

Ans: The primary approaches to root cause defects are:

  • Fishbone diagrams
  • Five Whys
  • Scatter plots
  • Failure Mode and Effects Analysis (FMEA)
  • Pareto charts

Q3. What is the difference between troubleshooting and RCA?

Ans: Troubleshooting and problem-solving methodologies generally solve specific problems. For instance, if an app's health monitoring exposes that the software instance is unresponsive or has crashed, the team might resolve the issue by restarting the software instance or rebooting the server.

Root cause analysis reveals the reason why the software becomes unresponsive; RCA might reveal a certain error condition where the app can't access the required data or cannot address the error as expected.

Q4. What is bug severity and bug priority?

Ans: Bug severity is the degree of impact caused on a system, while bug priority is the order of severity that has impacted the system. The severity usually relates to the standards and functionality of the system, whereas priority is related to scheduling.

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Root Cause Analysis for Software Defects — the what, why, and how

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