A side-sensitive synthetic chart combined with a VSS X‾ chart

•We study the performance of the mean chart.•We consider the side-sensitive signaling rule.•We consider a variable sample size scheme with two sample sizes.

In independent investigations, the variable sample size (VSS) scheme and the side-sensitive synthetic (SS) rule proved to reduce the delay with which the X‾ chart signals. Based on these findings we investigate the X‾ chart’s performance with the joint use of the VSS scheme and the side-sensitive synthetic rule. The SSVSS X‾ chart outperforms the pure VSS X‾ chart, especially when the risk of false alarms and the rate of inspected items per sampling cannot be high. In these cases, the VSS X‾ chart detects moderate mean shifts (around one standard deviation) in half of the time thanks to the side-sensitive synthetic rule.