A Method Of Calculating Process Capability Index For Non-Normal Distribution

In this paper, we primarily study the questions of process capability index for non-normal processes. After the method for calculating process capability index and the density estimation have gone deep into analyze on internal and overseas status quo,we discuss the method for calculating process capability index for non-normal processes. In this paper, we mainly do the following work:Firstly,it provides a new method for calculating process capability index for non-normal processes and improves discrete parameter on the basis of intensive study for the theory of process capability index. It unifies the standard between process capability index and discrete parameter, and hides the offset while represent it in the new discrete parameter.Secondly,it bring in a new type method for calculating the data of given case: Jonhnson inversion method and Box-Cox inversion method. We use these methods to deal with the same sample, then compare the results by them to check the effectiveness of the new method.Thirdly,superiorities and disadvantages of the two type method is also to be given. working conditions about the new method is in the after.What's more, we discuss some focus points in this field in this paper and summarize the conditions of usage for the new method.The paper is based on the main line of process capability analysis methods for non-normal processes. Statistics principle, mathematics derivation, comparative analysis and case study are employed to carry out the thorough examination to the theory of process capability analysis and control methods for non-normal processes. All of these construct a systematic evaluation for capability index for non-normal processes.