For an effective process capabily studies which is the number of standard deviation we take in account?

 

Process capability analysis (PCA) and Six Sigma methodology occupy important places in quality and process improvement initiatives. As a fundamental technique in any production, quality and process improvement efforts, PCA is used to improve processes, products or services to achieve higher levels of customer satisfaction. In order to measure process capability numerically, process capability indices (PCIs) have been developed. Six Sigma is widely recognized as a systematic methodology that employs statistical and non-statistical tools and techniques for continuous quality and process improvement and for managing operational excellence because it challenges to maximize an organization’s return on investment (ROI) through the elimination of nonconforming units or mistakes in the processes (Antony et al.,2005). The application of Six Sigma methodology provides reduction in variance and augmentation in the process capability, which is defined as the proportion of actual process spread to the allowable process spread that is measured by six process standard deviation units. Similar to Six Sigma methodology, in a process capability study, the number of standard deviations between the process mean and the nearest specification limits is given in sigma units. The sigma quality level of a process can be used to express its capability that means how well it performs with respect to specifications.

C.6

I support the answer of Mr. Jetley.

The answer is choice (A)

I would say6, to determine well the form of the Gaus- graphic and correctly the exact standard deviation

In statistics and probability theory, the standard deviation (SD) (represented by the Greek letter sigma, σ) measures the amount of variation or dispersion from the average.

If I understood this correct this would be2+4+6=12/3=4

Therefore my answer would be B)4

The correct answer is A .

For process capability studies we need sixsigma 

Six sigma process cpability means3.4 DMPO ( Defects Per Million Business Opportunities).

With6 sigma, defect probability is0.0003/ (per centage) then success probability is99.99979/ 

and cost of non conformance (non nquality) is less than10/ per cent .

Defect probability is nearly zero and success probability is nearly to perfect.

A.2