Six sigma and lean manufacturing are business improvement disciplines. Both utilize a different toolset to either solve a business issue or improve one. Some companies use lean manufacturing tools, others prefer six sigma, and some utilize both under the name "lean six sigma".

Many lean manufacturing and six sigma practitioners prefer one of the two disciplines, normally the one which they have knowledge and experience. While it’s certainly better to employ a discipline in which a person has knowledge and experience, this method minimizes the results.

Maximum results will be achieved through the use of both lean manufacturing and six sigma at the same time. It is also preferred to have each practitioner understand both methods rather than having experts within each field.

For example, a call center project could be developed to increase the average productivity of it’s 300 person workforce. The lean practitioner might look to reduce the waste, such as the time it takes to make or complete a call, length of time on call, time to find numbers, placement of lists, computers, and other objects. She might also look at the value per 8 hours, which is the actual "talk" time. If the telemarketer is on the phone 180 minutes out of 480, there is 300 minutes of non-value-added time. The concept of overall equipment effectiveness could also be utilized to determine the reasons for downtime and the waste included in the 180 supposed value time.

The six sigma practitioner might take a different view. They might look at the statistics of the operation and set up a DOE (design of experiments) to improve. For example, a few key statistics would be the various shift time, calls made versus those answered, call time, success rate with different caller and customer profile, and sales made at various call lengths and presentation. An experiment could be set up for various inputs, such as using two presentations at two different times placed from two different caller profiles. This would be known as a 3 factor (presentation, time, profile), 2 level experiment. A full factorial would utilize all 8 combinations.

Both examples of lean manufacturing and six sigma use above is just an example. Both disciplines utilize many different tools to accomplish the improved result. The point is the tools are different, but many business issues, opportunities, and challenges can be improved using both methods. In the example above, the lean manufacturing specialist might determine the exact placement of all materials, minimize wasted time searching, reaching, or waiting on information. Once the best layout and presentation and call method is established, it would be standardized. This is the methods of standardized operations, which is finding the best known method and repeating it every time.

The six sigma practitioner using the DOE would determine the optimum factors and levels above. Standard Operations could be employed to ensure it is repeated by all 300 employees.

Lean six sigma is approaches the opportunity by using either lean manufacturing, six sigma, or a combined tool use to maximize results. In other words, the problem determines the tools to use rather than forcing the use of a tool on the problem.

Six sigma black belts do receive some training in lean manufacturing and theory of constraints. Most lean manufacturing training includes very few six sigma tools. Lean six sigma training combines the use of both methods