The 5 Whys: A Root Cause Analysis Guide (With Examples)

Every morning, from 8 a.m. until noon, a Tech Leader and his team gather around the main accounting screen only to find that the transaction data was outdated. Although the system was designed to refresh the transaction list every hours, it only does so once every morning. This situation is causing a critical delay in decision-making and costing the company valuable time.

Root Cause Analysis in Action

Frustrated and determined, Marc, experienced in Lean Tech, initiated a Root Cause Analysis session with his team. Together, they began peeling back the layers of the “why” using the 5 Whys method. They discovered that the middleware was only receiving data once a day because their external data provider, after a recent system upgrade, had switched to a daily schedule. Yet, the root of the issue wasn’t just about data timing. It was about the weak technical partnership with the external provider.

Realizing that a stronger collaboration was needed, Marc reached out to the provider’s technical team. Through open discussions and joint troubleshooting, both sides agreed to implement a more robust integration strategy. This new partnership paved the way for hourly data updates, ensuring that Marc’s team had access to real-time financial insights. The change restored efficiency and reinforced the importance of continuous improvement and proactive problem-solving.

This story illustrates how a systematic approach to Root Cause Analysis can transform a frustrating daily challenge into a catalyst for strategic partnership and lasting improvement.

Understanding Root Cause Analysis

Root Cause Analysis (RCA) is a structured approach that goes beyond the symptoms of a problem. It leads to the source and core fact or event generating that problem.

We apply root cause analysis while solving problems. Indeed, effectively solving problems requires identifying and addressing their root causes. It is the only way of preventing the same problems from recurring and leading to long-lasting solutions.

The 5 Whys: A Deductive Root Cause Analysis Technique

The 5 Whys method is one of the most effective RCA techniques. It consists of asking “why” at least five times until you reach the root cause of a problem. From experience, stopping at two or three “whys” does not lead to the actual root cause.

Key points for using the 5 Whys:

• Be grounded in reality: At each level, go and see facts to verify it is a real cause — not an assumption.
• Trace back the causality chain: Work backwards to confirm that each cause directly generates the next.
• Adjust the depth: You may need more or fewer than five “whys” depending on the problem.

Identifying root causes is not purely mental reasoning. Each hypothesis requires validation through observation or experimentation where the work happens.

Below is a process designed to help you effectively identify root causes.

Root Cause Analysis Process

Prerequisites

• The problem has to be a performance gap and formulated accordingly. It requires a current and a target values or a prediction. It is also essential to differentiate the problem, its symptoms, and its impacts.
• Ensure the collection of all the relevant data about the problem. It may include performance metrics, process documentation, reports, or audit results. They help as sources of information while looking for the root causes.

In Marc’s case, clearly identifying the performance gap—where the accounting system failed to update data hourly—and gathering relevant data (like middleware logs and update timestamps) were crucial steps in pinpointing the root cause.

Step by step

1. Formulate one or several causes hypothesis. It starts with formulating one or several answers to why we are having the problem. It is essential to look at the process. Indeed, the problem is happening at a working step. You may spot potential causes along the previous steps and as far as possible: input documents, materials, equipment, people know-how, and more. At this stage, you have to resist jumping to conclusions. We have one or more causes hypotheses because there is no tangible evidence of the actual causes.
2. Use a root cause analysis framework. I recommend using the 5 Why’s, a deductive root cause analysis technique. It is an effective way to reach the root causes using a proven and structured approach.
3. Check the causality chain created so far. In reverse order, analyze each root cause and evaluate how it can lead to the problem under resolution.
4. Ensure the potential root causes are grounded in reality. You must accurately observe where things are happening or conduct experiments to check their relevancy. You may ensure that along the way, at steps 1 or 2.

Root Cause Identification Checklist

Identifying the root cause clearly is challenging, even with a simple process. Once you find a potential cause, use the checklist below for a detailed assessment.

• Lead to prevent recurrence: addressing this cause will stop the problem recurrence in a sustainable way, for your organization – specifically.
• Should require systemic change: like a new way of doing things, value stream changes or adaptation, new rules and policies.
• Is fundamental to the problem: it means that without it, the problem would not exist.
• Have evidence – or fact – support: we see evidence showing that it is the primary factor leading to the problem. It is about leaning on facts.
• Lead to actions with broader impact: addressing this cause should cover all the multiple symptoms – or causes – we see so far.

Example 1: Marc’s Case Study

The initial situation: Every day from eight o’clock in the morning till noon, the main screen of our accounting software does not show up-to-date transactions. 

The problem, as a performance gap: The software is refreshing the transactions’ list once a day instead of every hour.

Why? – level 1: The database does not update with new data hourly.

Why? – level 2:  The middleware only receives new data daily instead of hourly.

Why? – level 3: The external data provider now sends data once daily.

Why? – level 4: We have received no updates since our external partner upgraded their system.

Why? – level 5: We lack a method to develop and sustain a strong technical partnership with our external partner.

Specifically, our failure to establish and maintain a robust technical partnership with our external partner was a critical oversight that led to this problem. This scenario ultimately reveals a significant lack of know-how, which we consider as the root cause. Moreover, it touches upon every aspect of our root cause checklist.

Example 2: E-Commerce Data Architecture

A large e-commerce company notices a significant drop in website traffic and sales. The simple cause appears to be slow page load times. Let’s apply the 5 Whys.

Problem: Website traffic and sales have dropped 30% over the past quarter.

• Why? #1: Pages load too slowly, causing users to leave.
• Why? #2: Database queries take too long to execute.
• Why? #3: The database structure cannot handle current traffic volume.
• Why? #4: The data architecture was designed five years ago for 10x less traffic.
• Why? #5: No process exists to regularly review and update technical architecture.

Root Cause: Lack of architectural review process.

Addressing this root cause (implementing regular architecture reviews) solves multiple symptoms at once:

• Inefficient database queries
• Overloaded servers during peak times
• Difficulty implementing new features
• Inconsistent user experience across devices

This example demonstrates how a fundamental architectural issue can be the root cause of various performance problems. Fixing the root cause provides a lasting solution rather than treating each symptom individually.

Conclusion

Marc’s experience demonstrates that when you combine a structured RCA process with continuous improvement, you can turn daily challenges into strategic opportunities.

By properly identifying performance gaps—like the outdated data issue—and methodically uncovering their root causes using the 5 Why’s, his team resolved the immediate problem. They also forged a stronger technical partnership that brought lasting solution.

Embracing Root Cause Analysis (RCA) as a habit empowers your organization to move beyond temporary fixes and drive enduring improvements.