Understanding Root Cause Analysis
Published: 16 May 2007
This article examines the concept of Root Cause Analysis and its different types of tools.
by Uday Denduluri
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Root cause analysis forms the technique or tools that are used to determine the reasons for a problem occurring. We do this for solving the problem. In this article we will start by understanding a “Problem.” After doing so, we will analyze the roots that caused the problem. We will also discuss one type of Root cause analysis diagram, Fish bone Diagram, in detail with an example.

What is a Problem?

A problem can be defined as anything that is not going as per plan, per schedule or as it is expected to. The problem is very generic in nature. A problem can be an electric machine failure, an electronic component failure or a Mechanical failure. A human incompetence can also be treated as a problem: lack of motivation, lack of understanding, lack of technical competence, etc. But, let us try to confine it to software development and try to understand some problems related to it. Later we will try to analyze the roots that have caused the problem.

The developers see such kind of statements: “Development phase has been delayed by 2 weeks” or “Design does not suffice all the requirements.” All such kinds of problem will lead to some other problem known as “Schedule Variance.” Schedule is the plan for executing a project and Variance is the slippage of the plan. Hence, the main problem here is that Schedule Variance and sub-problems are “Improper/Incomplete Design,” “Human-Resource Attrition,” “Undocumented Artifacts,” etc. Any sub-problem can also be taken as a problem and analyzed further. This depends on the impact the problem creates.

Root Cause Analysis

In the above section we understood what a problem is. Now, once we encounter a problem we perform Root cause analysis. The Root cause analysis will be performed by the actions listed below.

- Understand the problem.

- Gather required information on the causes of the Problem.

- Identify all the Major and Minor Issues that created the problem.

- Find the root causes based on the evidences or Issues.

- Do recommendations targeting all the issues.

- Implement all the recommendations.

Figure 1

The input to the root cause analysis will be a problem and output to the Root cause analysis will be the solution that closes all the problems. Figure 1 tries to depict the same.

Root cause Analysis Tools

We have some predefined set of tools that help in the Root Cause Analysis. We choose the tool based on the problem that we encounter.

5 Whys – Mostly used with problems involving human factors or interactions.

Barrier Analysis – Treats the problem as a barrier and tries to remove the barrier.

Change Analysis – Mainly works on the Risk areas and tries to expose the same.

Failure mode and effects analysis – Commonly used to evaluate risk management priorities for mitigating known threat-vulnerabilities.

Fish-Bone Diagram or Ishikawa diagram or Cause and Effect Diagram – The fishbone will help to visually display the many potential causes for a specific problem or effect.

Pareto Analysis – A statistical technique in decision-making that is used for selection of a limited number of tasks that produces significant overall effects.

Fault Tree Analysis – Visual models showing the logical relationships between the equipment failures, human errors and external events that cause the problem.

Fish Bone Diagram

Dr. Kaoru Ishikawa, a Japanese quality control statistician, has invented the fishbone diagram. Hence, it is also referred as an Ishikawa diagram. Its analyses provide a systematic way of looking at effects and the causes that create or contribute to those effects. It looks like a fish skeleton when it is depicted which is why it is known as a Fish bone diagram. Let us understand how it looks before we take a scenario and try to explain the same.

Figure 2

As shown in the figure, the causes (Cause1, Cause2, Cause3 and Cause4) for the Effect have been shown. We use Fishbone diagrams for some of thes reasons stated below.

·         To study a problem/issue to determine the root cause.

·         To study all the possible reasons why a process is having difficulties or Problems.

·         Identifying the areas for data collection.

·         To study why a process is not performing properly or producing the desired results.

Let us now take a real time scenario and try to understand it.

Scenario – Schedule Variance of the Project life cycle is 30%

Factors – One of the major factors that lead to the schedule variance is insufficient requirements Analysis. Due to this, the design phase has gotten delayed and also effected, coding phase is also effected, the testing delayed, etc. Here, our problem or effect that we are currently discussing is about the schedule variance of the entire project and not a particular phase. Hence, we take into account all the factors (even if they are interdependent on each other).

Figure 3

Figure 3 shows a fishbone diagram explaining the problem “Schedule Variance.” One of the main causes shown in the figure is “Insufficient Requirements.” These can have sub-cause(s) like unrealistic project plan, which leads to insufficient requirements. Lack of domain knowledge can lead to insufficient requirements. Delay of requirements [Lack of requirements document] has led to delay in design phase. The lack of design documents leads to delay in the coding. Lack of motivation can lead to attrition rate of man power. All these causes have led to the schedule variance of the project up to 30%.



A problem can be defined as anything that is not going as per plan, per schedule or as it is expected to. We perform Root cause analysis for understanding the root causes of the problem and try to give a solution to the problem. It should be noted that Root Cause Analysis is not only used for problem solving, rather it can also be used for continuous process improvement. It can be also used for tracking and investigating. In some scenarios Root cause analysis is also used for measuring and reporting.

We have various Root cause analysis tools available: Viz. 5 Whys, Barrier Analysis, Change Analysis, Failure mode and effect analysis, Fishbone diagram, Pareto Analysis and Fault Tree Analysis. We have discussed the Fish bone diagram in detail with an example.


User Comments

Title: Root Cause Analysis   
Name: Chuck
Date: 2008-06-12 11:16:15 PM
You can get some free videos at
Title: More on Root Cause Analysis   
Name: Jane V.
Date: 2007-06-05 4:29:48 AM
Thanks for the overview. Another excellent source on Root Cause Analysis is: http://www.12manage.com/methods_root_cause_analysis.html
Title: Understanding Root Cause Analysis   
Name: Naveen
Date: 2007-05-17 7:25:45 AM
Some of the text in "Figure 3" of this article is not readable. Can someone upload a better picture?

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