## Various Definitions of Six Sigma

→ Different six types of definitions of Six Sigma are explained below with examples.

### Various Criteria for Defining Six Sigma

→ Six_Sigma is a very low variation focused near-zero allowances
→ It focuses on low defects generate by a process
→ Structured Methodology for improvements
→ It is a philosophy of keeping an eye on the target
→ Eliminate Focus on Inspection by catching defects early
→ Focus on profitability by bringing effective improvements

### Definition 1: Low Variation

→ If the process can accommodate six standard deviations (Ïƒ) between the process_mean and nearest
Specification limit, it is called as a Six Sigma Process.
→ In other words, we can say that the minimum numbers of standard deviation that are arranged between the process_mean and specification limits either side is called the sigma level of the process.
→ Let us assume, the process_mean is 14 the upper specification limit is 17 and the lower specification limit is 10.
→ We are assuming the standard deviation is 0.5.
→ So, between upper specification and process_mean, we can arrange 6 nos of sigma.
→ Similarly, we can arrange the 8 nos of sigma (standard deviation) between the process_mean and lower standard deviation.
→ Thus we need to take the minimum nos of standard deviations (Ïƒ) or in, In other words, we need to take the nos of sigma arranged between the process_mean and nearest specification limit.
→ Obviously, for this process USL is closer to process_means and we can arrange the 6 nos of standard deviations (Ïƒ) between them so this process is a Six_Sigma process.

### Definition 2: Low Defects

→ If the process makes 3.4 defects in a million opportunities over a long period of time, it is called as Six Sigma Process.

### Definition 3: Structured Methodology

→ DMAIC Methodology – For improving existing processes.
→ DMAIC stands for Define, Measure, Analyze, Improve, and Control. It's a well-structured methodology for problem solving and improvement.
→ You can check this article for DMAIC Methodology with Case Study.
→ DFSS or (DMADV) Methodology - this methodology is used for designing a new process or product.
→ DFSS stands for Design for Six_Sigma and DMADV stands for Define, Measure, Analyze, Design, and Validate.
→ Usually, the DMADV methodology is used where we have a specific design for the goal in our minds.

### Definition 4: Eye on Target, Not on Specification (A Philosophy)

→ As per Taguchi, any deviation From target is a loss to society.
→ We should Focus on the target as before we reach specification, the loss has started accruing.
→ Our traditional approach is if we are within the specification there is no loss, outside specification, there is a loss.
→ But as per Taguchi philosophy which is now six sigma philosophy any deviation from the target value starts contributing either loss to the customer or the supplier there for the loss to society.

### Definition 5: Eliminate Focus on Inspection, Catch Defects Early

→ The cost of the defect increases exponentially in the downstream.
→ Defect, if gets created, the customer will experience it, even with the best inspection methods.
→ According to six sigma philosophy, whatever the goodness of our inspection system the defects lead to customer de satisfaction.
→ For Example, we have a 90% efficiency of inspection, we are inspecting only once there will be 100000 defects making for the customer out of one million.
→ And if we keep on increasing the number of layers of the inspection we achieve six_sigma performance only after the sixth layer of inspection that is practically not possible.

### Definition 6: Money for Business

→ Six Sigma makes business sense as we are in the business of making money.
→ In the Six_Sigma Project, all Improvements can be categorized into three types of saving
1. Hard Savings,
2. Potential Savings, and
3. Soft Savings.

➨ The hard savings are the direct cost reduction and show the impact on the profit and loss directly.
→ For Example, if we reduce the manufacturing cost per product that will directly convert into the profit.
➨ Potential savings are the activities that improve the product, process, or performance and that will convert into money with the help of some additional effort.
→ For Example, if we increase the product sales have to effected for converting into cash. Such savings are called Potential savings.
➨ Soft savings are the savings that are beneficial for the organization in the long term and therefore emotional value is assigned to the improvements.
→ For Example, it covers the brand values, loyalty, and loyal customer, etc...