Cumulative sum (CUSUM) control chart has been proposed for detecting simultaneous shifts in the parameters of the Erlang-truncated exponential distribution. It was observed that the parameters of the CUSUM chart, that is, the lead distance and the mask angle change considerably for a slight shift in the parameters of the distribution.   The average run length (ARL) of the control chart also changes considerably for a slight shift in the parameters of the distribution.

cumulative sum chart, sequential probability ratio test, Erlang-truncated exponential distribution, lead distance, mask angle, average run length.