<p dir="ltr">Hi everyone,

<p dir="ltr">I&rsquo;ve spent some time reading about quality and process improvement, and I noticed that most people mix up these methods. I thought I&rsquo;d share a simple breakdown of how I understand them, in case it helps someone who is just starting out.

<p dir="ltr">Let&rsquo;s begin with root cause analysis. It means finding the real reason behind a problem instead of fixing only what you can see. If a machine stops again and again, restarting it is just a quick fix. A proper RCA analysis asks why it stopped, why that happened, and keeps going until the actual cause is found. The most common tools are the 5 Whys, the fishbone diagram and Pareto charts. A***d rule here is to look at the process and the system, not to blame one person.

<p dir="ltr">The Deming cycle, also known as dmaic, is the simplest of the group. It has four steps: Plan, Do, Check, Act. You plan a change, try it on a small scale, check the results, and then either roll it out or adjust it and repeat. It is based on early work by Walter Shewhart and became famous through W. Edwards Deming. Its biggest strength is that you don&rsquo;t need a big project or a special team to use it.

<p dir="ltr">Six sigma is a data-driven approach to reducing defects and variation in a process. It started at Motorola in the 1980s and later spread to healthcare, IT, banking and many other fields. When it is combined with waste reduction, it is called lean six sigma. The main method inside six sigma is DMAIC, which stands for Define, Measure, Analyze, Improve and Control. The DMAIC methodology is used when an existing process is not performing well. First you define the problem, then measure how the process behaves today, analyze the causes, make improvements, and finally put controls in place so the results last.

<p dir="ltr">Then there is 8D, also called the 8 disciplines of problem solving. It was developed at Ford and is common in automotive and manufacturing. It follows a fixed order: form a team, describe the problem, put a temporary containment in place so the customer is protected, find and verify the root cause, choose a permanent fix, check that it works, prevent it from coming back, and recognize the team. It is often used when there is a customer complaint, because it produces a clear written report.

<p dir="ltr">Here is how I see them fitting together:

<p dir="ltr">Root cause analysis is the skill used inside most of the other methods

<p dir="ltr">PDCA is a simple loop for testing and improving a change

<p dir="ltr">DMAIC is for bigger problems where you need data and measurement

<p dir="ltr">8D is for serious issues that need a team response and a report

<p dir="ltr">They are not really competitors. For example, you can use RCA tools in the Analyze step of DMAIC, and PDCA can be used to test a fix before rolling it out. The 8D root cause step and the DMAIC Analyze step also do a very similar job.

<p dir="ltr">For anyone who has used these at work, which one did you find easiest to start with, and did you ever combine more than one?