The effect of non-normality on the OC function of the sampling plan under EWMA is studied by deriving the OC function for a non-normal population represented by the first four terms of an Edgeworth series.
Mishra, U., Siddiqui, S. & Singh, J. R. (2019). Robustness of the EWMA Sampling Plan to Non-Normality. Journal of Modern Applied Statistical Methods, 18(2), eP2626. https://doi.org/10.22237/jmasm/1604188860