Quality Control Charts And Process Capability Index Related Issues

Quality control chart and process capability indices are important contents in continous quality control. They are valid tools for monitoring produce process in statistics state and reducing waster. Quality characteristic which follows skewed distribution or multivariate is important. In this paper, these questions are studied and some results are obtained as follows based on analyzing quality characteristic:1. Under population follow skewed distribution hypothesis, set up X and R control charts based on a weighted standard deviation. A numerical example is given by Monte Carlo simulation. Result shows that such charts are much superior than traditional Shewhart charts.2. Under population follow skewed distribution hypothesis, construct process capability indices for arbitrary skewed distribution based on a weighted standard deviation and analyse performance of these indices. Result shows that such indices are much superior than indices based on Shewhart method,Clements method and WV method.3. Analyse process yield index with multiple characteristics based on the results of single process yield index and the definition of multiple process yield index. The asymptotic distribution and statistical performance of these indices are given.4. Estimate process capability index by Bayesian method.Give it's lower confidence limits and sample size determination for lower confidence limits.