Six Thinking Hats as Applied in Six Sigma by Tata Consultancy Services

Six Thinking Hats – An Overview

Six Thinking Hats, a thinking “Tool Kit” developed by Edward de Bono, is a convenient way of putting into practice Parallel Thinking, which is totally different from an argument. The key to successful parallel thinking lies in taking charge of the thought process and guiding it to one direction at a time. The Six Thinking Hats method is revolutionary because it helps lay out all opinions side by side and zero in on a way forward, without any argument.

Focused thinking in a common direction (parallel thinking) speeds up the decision making process and takes advantage of the individual uniqueness that each person brings to the challenge. This is the key to innovative suggestions and potential solutions. Six Thinking Hats serves as a dissection tool allowing users to dissect the information into feelings, caution, benefits and ideas to arrive at an optimal solution.

There are six thinking hats, each having a different color. Each of the six hats represents different type of thinking. When you “put on” one of the hats, you operate exclusively in that mode of thinking.

Six Thinking Hats in Six Sigma

Six Sigma is a methodology for improving the capability of a process or reducing variability within a process. In any Six Sigma project if the Six Thinking Hats method is used, the intelligence, experience and knowledge of the entire project team are fully utilized before arriving at any decision.

Since, everyone associated with a Six Sigma project is looking and working towards the same goal, using the Six Thinking Hats technique, during a Six Sigma project can save time in taking decisions, speed up deliberations by removing ego problems and ensure that the subject in question is explored fully.

In short, Six Thinking Hats is a technique for stimulating and generating innovative ideas and solutions which can ease traffic jams caused by bumper to bumper thoughts and help improve the overall potential of Six Sigma in business improvement and development.

The Six Hats & Their Application in Six Sigma

Here is how one can use the Six Hats in Six Sigma improvement projects:

White Hat Thinking: Information known and Needed

The White Hat is like a white paper and deals with data and information. This hat assesses the relevance and accuracy of information, separates facts from speculation and notes both views when there is conflicting information.
Having a White Hat session before starting a Six Sigma project will go a long way in helping create a strong business case for projects. By providing accurate and relevant data, the project team can get a quicker buy in from the sponsors and other stakeholders. It will also help sponsors critically analyze the business case. We can also use the “Need to know” of a White Hat to arrive at the detailed project scope. This will help the project team focus on the correct area.

For example in a Six Sigma Project, the White Hat session during the Measure phase will help us a lot in creating data collection forms and defining specification limits for the selected output characteristics. Availability of data will help us set realistic and realizable targets.

Red Hat Thinking: Intuition and Feelings

The Red Hat deals with feelings, emotions and intuitions. Feelings may be based on experience and cannot always be quantified. But they can, nevertheless, be valuable ingredients in a discussion. The Six Thinking Hats system gives ‘feelings’ a significant place during the exploration of a subject.
The sponsor can put on the Red Hat while talking about the goal of the project and validating the same, though it may not be the only condition to validate the goal. Customers putting on the Red Hat can provide us with potential Six Sigma projects and a White Hat session should be conducted later on to delve deeper into the problem. For example in a Six Sigma Project, the Red Hat session can be a way for the customer to express himself in situations where he/she feels something is wrong, but cannot support the concern with suitable data.

The Red Hat thoughts are subject to change. For instance, the customer ‘s feelings can change from time to time. A White Hat session can also change the outcome of a Red Hat session. And since the White Hat session contains information or data, the data portion of a Six Sigma project can be used to translate the Voice of Customer.

Green Hat Thinking: Creativity and Alternatives

The Green Hat encourages creativity and demands the person wearing the hat to look for new ideas and alternatives or modify and remove faults in existing ideas. The Green Hat is used to look for possibilities even if they are remote thereby encouraging all participants to be creative.
The Green Hat session if coupled with Lateral Thinking techniques, can be a very powerful tool in the Improve phase when we are searching for solutions. It helps us tap the creative potential of all team members in the Six Sigma projects team and sets up a micro culture of creativity.

For example, the Improve phase of the Six Sigma Project can start with a Green Hat session to identify solutions. Lateral Thinking tools like PO and Random word can be used to generate ideas and then Harvesting used to pick up specific ideas. Also in improve phase, Lateral Thinking techniques like Challenge can be used to develop alternatives for the solution, fine-tune new processes and curtail unnecessary cost from the proposed solutions.

Black Hat Thinking: Cautions and Difficulties

The role of the Black Hat session is to point out areas of improvement in the outcome of different thought processes. It highlights the points of caution, existing and potential risks and concerns. The Black Hat session is a powerful, effective and essential ingredient in the thought process.
Whether it is a business case, a cost benefit analysis or causal analysis of potential reasons under 5 M and 1P, the Black Hat session will appraise us of the potential problems and risks. Having a Green Hat session after a Black Hat session will help in arriving at a better solution or take better decisions.

For example in a Six Sigma project, during the Define phase, we can use a Six Thinking Hats session to classify the VOC into Black Hats and Green Hats. We can treat the outcome of a Black Hat session with a Green Hats session and identify solutions. If Green Hats are in majority, it might point to DMADV project rather than DMAIC. We can use Black Hats along with their triggers like caution, risks, problems, difficulties and speculation to develop and fine-tune the business case.

Yellow Hat Thinking: Benefits and Feasibility

The Yellow Hat represents the logical and positive aspects of thinking. The Yellow Hat session looks for benefits and the return on investment for a particular solution. It reinforces the creative ideas and looks for new directions. The Yellow Hat session complements the Black Hat session.
The Yellow Hat session can help in defining a better business case. The same holds true for the Improve phase where a chosen solution needs to be justified against competing ideas. The Yellow Hat session can identify the differences, which are otherwise not visible. In a Six Sigma project, the Yellow Hat Session can be used on the goal achieved’ during the Control phase to justify the cost involved in the project. We can also use a Green or Yellow Hat session to unearth other improvement opportunities.

Blue Hat Thinking: Process Control

The Blue Hat session deals with process control. The Blue Hat session manages the thought process itself and plays the role of a facilitator. Any member of the group can wear Blue Hat.
The Master Black Belt typically wears a Blue Hat in Six Sigma Projects. The tollgate reviews serve as check points where the Master Black Belt reviews the project progress and findings. The Blue Hat session helps the Six Sigma project team to think in a focused manner and get the best out of all the participants.


There is no doubt that the integration of Six Thinking Hats with Six Sigma methodology will help the overall potential of Six Sigma in business improvement and development. With the Six Thinking Hats methodology, doing one thing at a time is encouraged. There is a time when the project team is on the lookout for risks and areas of improvement (Black Hat). Similarly, there is a time when they look for new ideas (Green Hat) and there is a time when the focus is on information (White Hat). Everything is not done at the same time. This helps bring in clarity in thought processes during the course of a Six Sigma project and helps teams come up with best-in-class solutions.


1. “Six Thinking Hats” by Edward de Bono
2. “Serious Creativity: Using the Power of Lateral Thinking to Create New Ideas” by Edward de Bono