Applying Zero-inflated Poisson Model for High-quality process Control Chart

• Main Authors: Yi-HengLin, 林翊亨
• Other Authors: Jr-Jung Lyu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/90999020600242766344

碩士 === 國立成功大學 === 工業與資訊管理學系專班 === 98 === Attribute c control chart is a Poisson distribution based on the central limit theorem (CLT). With the emergence of high-quality process, the number of defects was substantially reduced. However, the reduction in defects created an excessive amount of zero counts on the c chart. Additionally, it caused the control limit to approach zero or negative. The c control chart was led to invalid CLT assumptions and generated many false alarms. Therefore, the c chart was inadequate. Due to very few numbers of defects on process, the zero count was inadequate in monitoring and controlling attribute data in this high-quality process. Hence, searching for a more appropriate probability distribution is important. Due to the reasons mentioned above, the use of zero-inflated Poisson (ZIP) distribution will be more appropriate than Poisson distribution. In this research, a positive approach was proposed to prove the feasibility assessment of ZIP with a case study. In this paper, the Vuong test and maximum likelihood estimation method (MLE) was presented to estimate parameters, and then the average run length (ARL) applied for performance evaluation. This approach was ensured that ZIP model was a significant improvement and could be a useful reference for high-quality process.