Statistical Merits of U Control Chart when Using VSSI Sampling Policy

Many researches have shown that the variable sampling schemes are more effective than the traditional static ones in improving statistical measures. The average number of false alarms (ANF), the average number of samples (ANS), the average number of inspected items (ANI), and the adjusted average time to signal (AATS) are the most important statistical measures that have always been attending in the evaluation of control charts. In this paper, a comprehensive analytical review on the U control chart by the statistical measures have been explained. For this purpose, different levels of the possible factors are determined and presented the results of calculating the statistical measures with the obtained parameters on the sampling schemes of the U control chart. It is shown that, generally, the variable U control charts are able to improve the effectiveness statistical.

Keywords:

The average number of false alarms (ANF) , The average number of samples (ANS) , The average number of inspected items (ANI) , The adjusted average time to signal (AATS) , Attribute U control chart , variable sampling schemes