Process Improvement Methodologies - Part 3

Six Sigma

The third and final method of our process improvement series is Six Sigma. Six Sigma, just like Theory of Constraints, is a newer methodology. It was developed by Motorola and Bill Smith in the early 1980s. It uses statistical process control tools and a data-driven approach with a Continuous Improvement mindset, resulting in breakthrough improvements. Six Sigma methodology aims to minimize variation within a given process.

It employs a five-step approach termed DMAIC:

  • DEFINE the customer, their critical to quality (CTQ) requirements, and the core business process involved. Select the appropriate responses (the “Y’s”) to be improved

  • MEASURE the performance of the core business process involved by gathering data

  • ANALYZE the data collected to identify the root causes of defects, defectives, or significant measurement deviations whether in or out of specifications and opportunities for improvement

  • IMPROVE the target process by designing creative solutions to fix and prevent problems, reduce variability, or eliminate the cause

  • CONTROL and monitor the process to sustain the improvements (once the desired improvements are in place)

Six Sigma projects usually have a higher cost because they require a more in-depth analysis of the processes. Nevertheless, Six Sigma projects promise to create competitive advantage by meeting customer expectations in the most effective way.

Clearly, these have been very brief summaries of the three most commonly used process improvement methodologies. However, it is easy to see that all three methods have their areas of focus, though they share some of the same tools and have the same end-goal of improving the profits. When selecting the right method, it’s important to consider what the project at-hand calls for. For example, if you are dealing with a process that has too much variation and needs to be studied and brought under control, Six Sigma is the method to employ.

There are countless books and articles written about these methodologies and any operations management professional would benefit greatly from reading through at least a few to get a better understanding. For reading recommendations please email