This article proposes a Cumulative Sum (CUSUM) scheme, called the TC-CUSUM scheme, for monitoring a negative or hazardous event. This scheme is developed using a two-dimensional Markov model. It is able to check both the time interval (T)... more
This article proposes a Cumulative Sum (CUSUM) scheme, called the TC-CUSUM scheme, for monitoring a negative or hazardous event. This scheme is developed using a two-dimensional Markov model. It is able to check both the time interval (T) between occurrences of the event and the size (C) of each occurrence. For example, a traffic accident may be defined as an event, and the number of injured victims in each case is the event size. Our studies show that the TC-CUSUM scheme is several times more effective than many existing charts for event monitoring, so that cost or loss incurred by an event can be reduced by using this scheme. Moreover, the TC-CUSUM scheme performs more uniformly than other charts for detecting both T shift and C shift, as well as the joint shift in T and C. The improvement in the performance is achieved because of the use of the CUSUM feature and the simultaneous monitoring of T and C. The TC-CUSUM scheme can be applied in manufacturing systems, and especially in non-manufacturing sectors (e.g. supply chain management, health-care industry, disaster management, and security control).
