One-sided truncated EWMA control charts for monitoring two-parameter exponential distributed data

The two-parameter exponential distribution offers greater flexibility and suitability than the classical exponential distribution with a single scale parameter for modelling product lifetimes in reliability analysis and inventory management. Unlike existing schemes designed based on order statistics, new one-sided EWMA schemes using the truncation method are developed in this paper to monitor data following a two-parameter exponential distribution with sample sizes 𝑛=1 as well as 𝑛>1, indifferently. Furthermore, detailed instructions for constructing the Markov chain model and the Monte Carlo simulation are provided to investigate the detecting properties of the recommended schemes, along with cross-validation to verify their effectiveness. Meanwhile, detecting performance comparisons between the proposed lower-sided scheme and the latest relevant scheme are carried out. The simulation results demonstrate that the proposed chart is not only superior to the comparative chart in monitoring efficiency and its resistance to biases in average run length (ARL) and average time to signal (ATS), but it is also more straightforward and accessible for practitioners. Finally, two illustrative examples are presented to demonstrate the implementation of the proposed schemes.