COMPARISON METHOD PROCESS CAPABILITY INDICES FOR NORMAL AND NON-NORMAL DATA BY USE SIMULATING.

Abstract

In quality control assume that the distribution of their process output is normal. Thedefinition and estimation of (pci) indices are usually based on the assumption that theproduction process under normal distribution. But, in most practical cases this assumptionis not valid and the distribution of the quality characteristics may follow non-normaldistributions such as Weibull ,Lognormal , and Exponential distribution). One can see thedifference between the non-normal process capability indices and the normal processcapability indices by overlooking its theoretical distributions .This paper provides a decisionon how to calculate the process capability indices for normal and find process capabilityindices another step transformation data by (Box – Cox( and Johnson transformation andcomparison between two methods.