COMMERCE 2OC3 Lecture Notes - Lecture 15: Statistical Process Control, Lookup Table, Natural Number
16 Apr 2018
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Spc uses the tool control chart to detect assignable variation i. e. , to detect if the distribution is stable. The mean of the distribution is stable (by x-chart) The range (a measure of variability) is stable (by r-chart) Find the upper range factor d4 and lower range factor d3 from a lookup table. Collect samples (often 20 to 25, each consists of 4 or 5 observations) Step 2: construct the mean chart and the range chart. Step 3: investigate points that are out of control. Assign causes to those anomalies, address the causes, then resume the process. Step 4: collect additional samples; revalidate the control limits using new data. Defect or non-defect, good or bad, acceptable or unacceptable (categorical values) Counting number of defects per unit of output (integer values) For every sample, measure the fraction of defective items. For every sample, measure the number of defects. Like the x-chart, p-chart & c-chart are also based on hypothesis testing.
