![]() Whereas in a 6 Sigma process, the values are closer to the centre line showing less variation in the process. In a 3 sigma process the values are widely spread along the centre line, showing the higher variation of the process. If a given set of data has normal probability distribution, then the number of defects that will occur in the process over a period of time can be known depending upon the sigma level of the process. It is a measure which uses the characteristic of past data to make judgements about how the process will perform in the future. Sigma or standard deviation is a statistical measure of dispersion in data. It focuses on the bottom-line and is a proven methodology for problem solving. It can also be used to bring breakthrough improvements in the process. ![]() In other words, it is a methodology to achieve 3.4 defects per million opportunities. It requires thorough understanding of product and process knowledge and is completely driven by customer expectations. Six Sigma is a data-based methodology to improve performance by reducing variability. It was initiated by Bill Smith at Motorola in 1986. Details of how to compute Sigma for any process is covered in detail in our Six Sigma Green Belt Course.Let us first understand what is six sigma, 6σ is Way of systematically improving processes by eliminating defects or in other words we can say that “Six Sigma” refers to the notion that if you have six standard deviations between the mean and the nearest specification limit, practically nothing will exceed the limits. Let’s say your process isn’t at Six Sigma then to find out the sigma value you can either use Sigma Capability Table, Normal Distribution Table or Sigma Calculator.Assess if the Standard Deviation or Sigma of the process is small enough, that 6 Sigmas can be fitted on either side of the customer requirement window.Use the data of process performance to compute the standard deviation.Understand what the customer requirement is? If there is a window within which the customer wants her delivery or quality, then that becomes your customer requirement. To sum up, if you want a particular process to be at Six Sigma, then you will have to manage the following: Let’s say for your friend’s process, only 5 standard deviations or sigmas can be fitted on either side of the bell-shaped curve, then, his sigma capability is at 5 or his newspaper delivery process is at 5 Sigma. We covered the computation of standard deviation in ‘What is Sigma in Six Sigma’. It depends on the value of Standard Deviation. So, it is very obvious that your newspaper delivery isn’t at the Six Sigma level, but your friend’s delivery could be. 3 or 4 days) of the delivery will be beyond your requirement. ![]() For the newspaper example, it means that if there are 1 million days of newspaper delivery, only on 3.4 days (i.e. Based on the principle of bell-shaped curve (normal curve), 6 Sigma equals only 3.4 defects per million opportunities. When it’s Six, it means that the Standard Deviation or Sigma is so small that 6 Standard Deviations or 6 Sigmas can be fitted on either side of the bell-shaped curve. ![]() In this case, the newspaper delivery process. Six refers to the Sigma Capability of any process. Now, let’s answer the question ‘What is Six in Six Sigma?’
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |