期刊名称：Brazilian Journal of Probability and Statistics
印刷版ISSN：0103-0752
出版年度：2006
卷号：20
期号：2
页码：133-140
出版社：Brazilian Statistical Association
摘要：We propose in this paper an improved u chart for monitoringλ, the average number of defects per inspection unit, which can achieve largeimprovement over the usual u chart for attributes. This chart is correct toorder O(n.3/2), where n is the sample of inspection units, and is also a betterimprovement over the modified u chart proposed by Chen and Cheng (1998)which is correct only to order O(n.1). We compare both modified u chartswith the usual u chart
关键词：Cornish-Fisher expansion; normal approximation; Poisson;distribution; u chart
