Purpose: To study the impact of sampling inspection on TBE charts or simply T charts of four types namely, a Shewhart chart, a CUSUM chart, a SA T chart, and a curtailed SA T chart. Summary: The T chart for examining the time interval T between events has been attracting increasing interest in recent years. They are effective in high yield production lines with low defect rates. They can also be applied to service industries like healthcare. The objective is to have longer duration of time intervals between failures. Also continuous shift in time intervals are of concern and not freak changes. Many types of T charts are being used such as Shewhart T chart, exponential T chart, TCUSUM chart, sequential analysis (SA) T chart, etc. for handling various types of situations. Though most these charts are for 100% inspection, there are instances of use of these charts for sampling inspection where tests are destructive in nature. SA charts are most powerful in detection of speed compared to other charts and also need only low sample size. The sample size for this chart is a random number and not a fixed number. SA chart's sample size depends on the data observed at the current sample point and is effective in producing the signal for out-of-control situation in the first sample itself. Once curtailment is incorporated in the SA chart, then it will enhance the detection effectiveness of the SA T chart. This article studies four T charts under sampling inspection such as Shewhart T chart, CUSUM T chart, SA T chart, and curtailed SA T chart. In sampling T chart the sum of the number of sampling intervals is checked for conformance. If the observed value is smaller than the target then the situation is out-of-control and needs corrective action. (36 refs.)
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