A Moving Average Control Chart for Monitoring the Fraction Non-conforming

摘要

The p chart is often used to monitor the fraction of non-conforming products. However, the p chart is slow in detecting sustaining shifts of small magnitude in the level of fraction non-conforming. This paper discusses a more efficient alternative to the standard p chart approach, i.e. the construction of a moving average control chart for fraction non-conforming, p. Approximations by means of mathematical calculations and the corresponding simulation results for the average run length profiles show that the performance of the new approach is superior to that of the standard approach. The new approach is easy to implement and hence might be attractive and useful to practitioners. Examples are also given to show how the proposed procedure is put to work in real situations.