Abstract:
Runs-rules are typically incorporated in control charts to increase their sensitivity to detect small process shifts.
However, a drawback of this approach is that runs-rules charts are unable to detect large shifts quickly. In this
paper improved runs-rules are introduced to the nonparametric sign chart, to address this limitation. Improved
runs-rules are incorporated to maintain sensitivity to small process shifts, while having the added ability to
detect large shifts in the process more efficiently. Performance comparisons between sign charts with runsrules
and sign charts with improved runs-rules illustrate that the improved runs-rules are superior in
performance for large shifts in the process, while maintaining the same sensitivity in the detection of small
shifts.
