This article considers the stress-strength reliability of a coherent system and discusses its computation based on the concept of system signature. The system components may experience the same or different stress levels. We have found some mistake results given by Eryilmaz (2008). Some other mistake results of Bhattacharya and Roychowdhury (2013) was pointed out by Sadegh (2021). All these mistake results are due to misapplication of the system reliability in case of the system components are subjected to a common stress level. It is shown that the system signature can be used for calculating of the stress-strength reliability of a coherent system with different stress levels whereas when the system components are subjected to a common stress level, the use of system signature may leads to a mistake result. Regarding this, some mistake results given in Eryilmaz (2008) are pointed out.

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