ISSN : 2005-0461(Print)
ISSN : 2287-7975(Online)
ISSN : 2287-7975(Online)
Journal of Society of Korea Industrial and Systems Engineering Vol.20 No.43 pp.205-209
u 관리도에서 단위당결점수 변화 탐지
Detection of Changes of Mean Nonconformities per Unit in the u Control Chart
Abstract
One objective of the u control chart is to detect changes of mean nonconformities per unit occurred owing to various causes. This paper shows the detection probability using the Poisson distribution for various parameters, that is, subsample size n, mean nonconformities per unit uo, and $uochange ratio k. We find that (1) as uo increases the smaller n is required for the same detection probability and the same change ratio; (2) as k gets away from 1 the smaller n is required; (3) the bigger n is required for the bigger detection probability. Several tables are given from our findings and are hoped to be used as guidelines for u chart users.