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Green Belt Lean Six Sigma Training – Week 4

The fourth week of this challenging training was focussed on the last part of the Six Sigma model, the improve and control stage. The first thing that came to mind during this lecture was the following: shouldn’t you first control the processes before you improve them? This is also part of my thesis subject since two of my research questions focus on the control and improvement of the core processes of my company. At first, I wanted to start with the process control, followed by improvement. However, this course convinced me to do it the other way around. After reading this article, I hope that you agree.


In the previous articles, I explained that the stages: define, measure and analyse will help a company to find the root causes of their process/product insufficiencies. If the causes are clear, steps can be taken to solve them and improve the process. The lecturer mentioned several brainstorm techniques that can be used to come up with the right solutions. After collecting many potential solutions, you have to filter them out, for instance by using critical analysis and graphical representation techniques. Before you can implement the most effective solution, you have to develop a proposal about the timeframe, cost, advantages etc. It is crucial to involve the stakeholders in this process and they have to approve the solution and work with it. Even if they cannot influence the solution itself, you cannot keep them in the dark.

The next step is the planning and implementing of the solution. In some cases, a pilot is necessary to test the effects of a solution. This can be the case if the solution is far reaching, costly or difficult to reverse. The pilot and the implementation itself can be labelled as a project within a project. Therefore, tools of the define phase can be used again (e.g. the project charter).  A risk-based-thinking method is advisable, meaning that before you start the implementation, think about things that could go wrong. You should assess risks based on the frequency, the severity and the necessary recovery time.

When the solution is ready to get implemented the hardest part is to make the change. Process improvement is all about change management and convincing people that they have to change for the better. You can make a perfect plan, but without support it is doomed to fail. Thus, inform your stakeholders, understand their resistance and improve the process with them!


The last step of the Six Sigma model is about controlling the process. Now adjustments have been made and the process has been defined, measured, analysed and improved. In addition, the process should be kept in control as well. To sustain a controlled process, the processes need to be standardized, monitored and documented.

In the control stage, very known principals return. Firstly, the customer requirements play an important role as the process should meet the requirements of the customer. If the process contains too much variation in its outputs, the process is not controlled well. To measure this, statistical methods are applied again. It is not only about measuring if the process stays between the calculated boundaries, but it should also be about identifying patterns in the data. The patterns can be used to identify the ‘common’ and ‘special’ causes. To prepare for a process that is ‘out of control’, meaning that it does not perform as it should, a contingency plan should be developed. This plan helps you to efficiently deal with unexpected errors. The lecturer gave us a valuable advice by stating that  if the process gets out of control, do not start twisting knobs, but pull the plug, stop the process and start searching for possible causes.

Now the improvement and control stages are explained. It is hopefully clear why I mentioned that process improvement should be done before controlling the process. Improvement is about changing the process, overcoming resistance and solving internal problems. It would be a waste of resources if you start with developing process controls (standardizing and documentation), which are then followed by improvements (changes).

This article was not only meant to tell you about the last stages of the Six Sigma model, but I also hope that this article made clear that the obvious is not always correct, and you should sometimes turn things around. This could be a valuable advice in the development of your master thesis proposal and future career.

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