This article presents simpler alternative formulae and procedures of implementation to deal with the relative range statistic used in the range control chart for process dispersion monitoring. The chart performance is assessed considering false alarm comparison between our exact limits charts versus normal approximated ones, which shows the serious drawbacks of such misplaced control limits. These much simple tools introduced here, we believe, will permit the presentation of R charts more transparently and without unrealistic normal approximations, avoiding the serious limitations of such “ad hoc” practice.
['Emanuel Pimentel Barbosa', 'Mario Antonio Gneri', 'Ariane Meneguetti']
Range Control Charts Revisited: Simpler Tippett-like Formulae, Its Practical Implementation, and the Study of False Alarm