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Thu 28 Apr, 2011 04:10 am
May I know why ARL is always bigger than MRL when shift is zero or small when they have same lambda, control limit, sample size for a EWMA chart?
Thanks.
@facebook195,
The distribution of an exponentially weighted moving average is highly skewed so average run length is higher than the median run length.
http://www.informaworld.com/smpp/content~db=all~content=a772467992~frm=titlelink
http://en.wikipedia.org/wiki/EWMA_chart