Adapting EWMA Control Charts for Batch-Correlated Data

摘要

Batch production is common in the chemical and process industries. This article demonstrates how EWMA charts should be modified to account for substantial batch-to-batch variation. A batch-correlation model is considered, and methods of estimation and hypothesis testing for the batch-correlation coefficient are developed. This discussion is most appealing for production processes in which items are processed in batches but are related within batch.