A control chart based on likelihood ratio test for detecting patterned variance shifts
نویسندگان
چکیده
Most SPC approaches for detecting the process variance assume that it remains constant over time. However, these approaches may not be well handled with the case in which patterned changes exist. In this paper, we propose a new control chart which integrates EWMA procedure with generalized likelihood ratio (GLR) test statistics for monitoring patterned variance shifts. It can be easily designed and implemented with its reference-free property. Due to the good properties from GLR test and EWMA procedures, our chart provides an effective and robust detecting ability for various types of shifts.
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