Overview

Root Cause Analysis (RCA) involves application of a series of problem solving methods used to identify the root causes of problems or issues. These techniques produce a systematic, quantified and documented approach to the identification, understanding and resolution of the underlying cause. By implementing the corrective measures of the root causes, the likelihood of problem recurrence is minimized. However, it is recognized that complete prevention of recurrence by a single intervention is not always possible. Thus, RCA is often considered to be an iterative process, and is frequently viewed as a tool of continuous improvement.

While performing root cause analysis (RCA), all possible causes are captured by using techniques like Brainstorming, Cause Effect Diagram / Ishikawa Diagram, etc. Once captured, the irrelevant causes are eliminated. If the identified possible causes are minimal (1 or 2), then the “5 Why” technique is used to arrive at the root cause. In case the possible relevant causes are > 2, then pareto analysis should be performed to arrive at the root cause. The root cause and the actions to eliminate them must be documented. A cost benefit analysis must be performed to verify if the actions are feasible or justifiable. If there is a cost benefit seen, then the corrective action should be implemented. Thus, conducting a Root Cause Analysis gives the confidence that the problem can be solved by taking a structured approach, thereby preventing the recurrence of the problem.

Root Cause Analysis Tools And Techniques

There are a number of techniques that can be implemented for root cause analysis. The most common ones are described below.

Five Whys

5 Why’s typically refers to the practice of asking, five times, why the failure has occurred in order to get the root cause of the problem. Repeat asking “Why” until the root cause is reached. This may be more or less than five whys. No special process is required to apply this technique and the results are mostly captured in a spreadsheet. 5 Why’s are best used when tackling simple RCA.

Although a generally accepted technique, few drawbacks of this technique include:

• Tendency for investigators to stop at symptoms rather than going on to lower level root causes.
• Inability to go beyond the investigator's current knowledge - can't find causes that they don't already know
• Lack of support to help the investigator to ask the right "why" questions.
• Answers to the Whys differ based on who is asked.

Pareto Analysis

Pareto Analysis is a statistical technique in decision-making used to select a limited number of tasks that produce significant overall effect. It uses the Pareto Principle (also known as the 80/20 rule) the idea that by doing 20% of the work you can generate 80% of the benefit of doing the entire job. In this context, this analysis implicates 80 percent of the problems may be caused by as few as 20 percent of causes. To use pareto analysis, identify and list problems and their causes. Then score each problem and group them together by their cause.

Here are the 8 points to consider while plotting a Pareto Chart:

• Create a vertical bar chart with causes on the x-axis and count of number of occurrences on the y-axis.
• Arrange the bar chart in descending order of cause importance that is, the cause with the highest count first.
• Calculate the cumulative count for each cause in descending order.
• Calculate the cumulative count percentage for each cause in descending order. Percentage calculation: {Individual Cause Count} / {Total Causes Count} *100
• Create a second y-axis with percentages descending in increments of 10 from 100% to 0%.
• Plot the cumulative count percentage of each cause on the x-axis.
• Join the points to form a curve.
• Draw a line at 80% on the y-axis running parallel to the x-axis. Then drop the line at the point of intersection with the curve on the x-axis. This point on the x-axis separates the important causes on the left (vital few) from the less important causes on the right (trivial many).

Cause and Effect Diagrams

Cause and Effect diagrams (also called Ishikawa diagrams or fishbone diagrams) are a technique to graphically identify and organize many possible causes of an issue. Possible causes are grouped into major categories to identify the sources of the underlying cause. These are then narrowed down to sub causes which need to be addressed. These diagrams help teams to identify the most likely cause of the problem. Cause-and-effect diagrams are designed to:

• Stimulate thinking during a brainstorm of potential causes.
• Provide a structure to understand the relationships between many possible causes of a problem.
• Give people a framework for planning what data to collect.
• Serve as a visual display of causes that have been analysed and studied.
• Help team members communicate within the team and with the rest of the organization, the various reason for the problem.

Causes can be derived from brainstorming sessions using the following steps.

• Determine the problem to be analyzed. Make sure that the problem is specific, tightly defined and relatively small in scope.
• Determine the major categories that could be the possible cause. The categories typically include:
  • People: Anyone involved with the process
  • Methods: How the process is performed and the specific requirements for doing it, such as policies, procedures, rules, regulations and laws
  • Machines: Any equipment, computers, tools etc. required to accomplish the job
  • Materials: Raw materials, parts, pens, paper, etc. used to produce the final product
  • Measurements: Data generated from the process that are used to evaluate its quality
  • Environment: The conditions, such as location, time, temperature, and culture in which the process operates.

Note: these categories may not fit every situation and different categories might be appropriate. However, the total number of categories should not exceed six.

• Enter the problem in the Effect box and the categories identified in the spines.

• Brainstorm all possible causes and label each cause under the appropriate category

• Once all the desired causes are captured, prioritise the ones which are under the control and concentrate on finding solutions for the prioritized causes.

Cost Benefit Analysis

A Cost-Benefit Analysis (CBA) is a process by which business decisions are analyzed. It is a systematic approach to estimate the strengths and weaknesses of alternatives. It is used to determine options that provide the best approach to achieve benefits while preserving savings The CBA is also defined as a systematic process for calculating and comparing benefits and costs of a decision.

CBA has two main purposes:

• To determine if an investment/decision is justifiable or feasible by verifying whether its benefits outweigh the costs, and by how much.
• To provide a basis for comparing projects, which involves comparing the total expected cost of each option against its total expected benefits.

Following are the steps involved in performing a Cost Benefit Analysis:

• Define the goals and objectives of the project/activities
• List alternative projects/programs
• Select measurement(s) and measure all cost/benefit elements
• Predict outcome of cost and benefits over a period of time
• Convert all costs and benefits into a common currency
• Calculate the profit from among the adopted options
• Perform sensitivity analysis (uncertainty analysis)
• Adopt recommended choice.