Cumulative count of conforming chart with variable sampling intervals

The control chart with cumulative count of conforming (CCC) items has shown to be useful for process monitoring in automated and discrete manufacturing. It does not require a fixed sample size and can be useful for one-at-a-time data. The current research relies on data from the fixed sampling interval (FSI) scheme. In this paper, we investigate the use of the CCC chart when the variable sampling interval scheme is used. The average time to signal (ATS) is calculated, and its efficiency is compared with that of FSI CCC chart. The use of variable sampling interval scheme may further enhance the cost effectiveness of control chart implementation from a practical point of view. (c) 2005 Published by Elsevier B.V.