Exponentially weighted moving average (EWMA) charts can be used to detect small shifts in a process. Each point on an EWMA chart is the weighted average of all the previous subgroup means, including the mean of the present subgroup sample. The weights decrease exponentially going backward in time. For more information about exponentially weighted moving average charts, see Box et al. (2009) and Montgomery (2013).
The EWMA Control Chart platform pairs an EWMA chart with an X chart and a residual chart. If you do not specify a Subgroup variable, the X chart is an individual measurements chart. If you specify a Subgroup variable and at least one subgroup size is greater than 1, the X chart is an XBar chart.