conclusion
The purpose of this paper is to investigate the ANF, ANS, ANI, and AATS
statistical measures by applying variable sampling schemes in the U
control chart. The U control chart is the statistical process control
tools and used to count the number of defects in samples of a product.
In designing variable sampling schemes, the range of sample size and/or
sampling interval is unpredictable. Variation in sampling may be
unpleasant from an operational viewpoint, but as shown, significant
statistical improvement has been generated in the process. In this
paper, the design of the sampling schemes and evaluation of statistical
measures was done based on the Markov chain approach and transition
probability of different process states. Also, by comparing the
numerical results, the VSSI sampling scheme, which uses two sample sizes
and two sampling intervals, compared with other schemes, has led to more
reduction in the statistical measures and increase efficiency in the U
control chart. Therefore, the significant advantage of the VSSI sampling
scheme with other schemes, especially the FSSI, recommend in practical
applications for more accuracy and better results.