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Root Cause Analysis is a useful process for understanding and solving a problem. As an analytical tool, Root Cause Analysis is an essential way to perform a comprehensive, system-wide review of significant problems as well as the events and factors leading to them.
Root Cause Analysis (RCA) is a technique that helps you answer the question of why the problem occurred in the first place. Root Cause Analysis aims to identify the origin of a problem. It uses a specific set of steps to find the primary cause of the problem so that you can: Determine what happened, Determine why it happened & Figure out what to do to reduce the likelihood that it will happen again.
Principles:
– Focusing on corrective measures of root causes is more effective than simply treating the symptoms of a problem or event.
– RCA is performed most effectively when accomplished through a systematic process with conclusions backed up by evidence.
– There is usually more than one root cause for a problem or event.
– The focus of investigation and analysis through problem identification is WHY the event occurred, and not who made the error.
Three Basic Types of Causes:
1. Physical Causes
– Tangible, material items failed in some way (for example, a water ingress alarm stopped working).
2. Human Causes
– People did something wrong or did not do something that was needed. Human causes typically lead to physical causes (for example, no one checked the alarm circuit, which led to the sensor failing).
3. Organizational Causes
– A system, process, or policy that people use to make decisions or do their work is faulty (for example, no one person was responsible for sensor maintenance, and everyone assumed someone else had checked).
– Root Cause Analysis (RCA) represents comprehensive investigation, assessment, evaluation, and correction. There are many types of investigative procedures used to carry out Root Cause Analysis.
Steps in Root Cause Analysis:
There are 7 steps in the Root Cause Analysis process which are as follows:
Types of Root Cause Analysis:
1. Brainstorming Technique
2. Fishbone/Ishikawa diagram
3. 5W and 1H Techniques
4. Corrective action and Preventive action (CAPA)
5. Affinity Diagrams
6. Pareto Diagram
7. Failure Mode and Effects Analysis (FMEA) etc.
1. Brainstorming Technique
– This is one of the creative, problem-solving methods that allow people to come up with suggestions/ideas that could help, solve the problem, or help to identify the root – cause of the problem.
– A meeting with the cross-functional team may be called to identify the root cause, of such a brainstorming session.
– Relevant people will be asked to think and their views of the problem and suggest their views to reach the root cause, and solve the problem.
– All views and suggestions shall be analyzed to identify the cause of the problem.
2. Fishbone/Ishikawa Diagram
– The fishbone diagram identifies many possible causes for an effect or problem.
– The Fishbone diagram includes the potential cause of the problem and is used in order to find the real causes.
– This tool is mainly categorized in 6M i.e. Man, Materials, Machine Method, Measurement, Mother Nature. Below are the main 6M causes:
i. Man: Responsible persons who involved in the process or activity.
ii. Materials: Raw materials, items, parts used or involved in the process or activity.
iii. Method: It includes all procedures, rules, policy, regulation, and specific requirement for the activity or process
iv. Measurements: Data generated during the a process which measures the quality of products.
v. Machines: Any equipment, instrument involved in the activity or process.
vi. Mother nature: This include environmental conditions like temperature, humidity, pressure differential etc. and culture in which process or activity performed.
3. 5W and 1H Techniques
– 5W1H (who, what, where, when, why, how) is a method of asking questions about a process or a problem taken up for improvement.
– Four of the W’s (who, what, where, when) and the one H is used to comprehend for details, analyze inferences and judgment to get to the fundamental facts and guide statements to get to the abstraction.
– The last W (why) is often asked five times so that one can drill down to get to the core of a problem.
– 5W1H of Six Sigma explains the approach to be followed by exactly understanding and analyzing the process, project, or problem for improvement.
4. Corrective Action and Preventive Action (CAPA)
CORRECTIVE ACTION It is an extension of root cause analysis. The first goal of CA is to find the root cause, base event or error that preceded the problem. The second goal is to take action directed at the root cause or error.
PREVENTIVE ACTION It is similar to Lessons Learned/ Read Across. PA resembles the replication activity of design for six sigma (DFSS). Another PA in industry is Yokaten, a Japanese term used by Toyota, describing a sharing across the organization. The primary goal of PA is to inform an organization and prevent the problem from returning to other facilities lines or products.
5. Affinity Diagrams
The final root cause analysis tool is affinity diagrams. Often the output from a brainstorming session, an affinity diagram can be used to generate, organize, and consolidate information related to the issue in question.
After ideas have been generated, they can be grouped according to their similarity to identify the major causes. An affinity diagram should be used to stimulate discussion about a problem or issue, opening up possibilities for improvement or solution.
6. Pareto Diagram
– A Pareto chart is a histogram or bar chart combined with a line graph that groups the frequency or cost of different problems to show their relative significance. The bars show frequency in descending order, while the line shows cumulative percentage or total as you move from left to right.
– Pareto charts are one of the seven basic tools of quality described by quality pioneer Joseph Juran. Pareto charts are based on Pareto’s law, also called the 80/20 rule, which says that 20% of inputs drive 80% of results. Of course, it may take asking why more than five times to solve the problem the point is to peel away surface-level issues to get to the root cause.
7. Failure Modes and Effects Analysis (FMEA)
– FMEA is a well-defined tool that can identify various modes of failure within a system or process. In many companies, if a major problem is detected in the process or product, the team is required to review any existing FMEAs in relation to the problem.
– The team should determine if the problem or effect of the failure was identified in the FMEA and if it was, how accurately the team evaluated the risk. If the problem is not included in the FMEA, the team should add any known information and then complete the following steps:
— List the current problem as a failure mode of the design or process.
— Identify the impact of the failure by defining the severity of the problem or effect of failure.
— List all probable causes and how many times they occur.
— When reviewing a process FMEA, review the process flow or process diagram to help locate the root cause.
— Next identify the Escape Point, which is the closest point in the process where the root cause could have been detected but was not.
— Document any controls in place designed to prevent or detect the problem.
— List any additional actions that could be implemented to prevent this problem from occurring again and assign an owner and a due date for each recommended action.
— Carry any identified actions over to the counter-measure activity of the RCA.
