Unformatted text preview: 3σ) is about 0.99. 95% 99.74% 4QA3 F12  3σ  2σ  1σ µ=0 A. Gandomi 1σ 2σ 3σ 19 ● Variable data: o Length, size, weight, height, time, velocity ● Attribute data: o Good/bad, yes/no o Number of scratches on a car, number of defects per yard of cloth 4QA3 F12 A. Gandomi 20 To determine if the process variation appears to have changed signi3icantly. In most cases, one is concerned only if variation increases signi3icantly, so that the lower control limit is often taken to be 0. 4QA3 F12 A. Gandomi 21 1. Form subgroups typically of size 4 or 5. 2. Compute the range of each subgroup. The range is the difference between the largest and smallest observations within a subgroup. 3. The upper and lower control limits are given by: LCL = d3 R
UCL = d 4 R
where R is the average of the ranges and d3 and d 4
are constants that depend on the subgroup size.
4QA3 F12 A. Gandomi 22 SAMPLE SIZE FACTORS FOR R CHART n d3 d4 2 3 4 5 6 7 8 9 10 . . . 20 4QA3 F12 0.00 0.00 0.00 0.00 0.00 0.08 0.14 0.18 0.22 . . . 0.41 A. Gandomi 3.27 2.57 2.28 2.11 2.00 1.92 1.86 1.82 1.78 . . . 1.59 23 SAMPLE k 1 2 3 4 5 6 7 8 9 10 4QA3 F12 OBSERVATIONS (RING DIAMETER, CM) 1 5.02 5.01 4.99 5.03 4.95 4.97 5.05 5.09 5.14 5.01 2 3 4 5 x R 5.01 5.03 5.00 4.91 4.92 5.06 5.01 5.10 5.10 4.98 4.94 5.07 4.93 5.01 5.03 5.06 5.10 5.00 4.99 5.08 4.99 4.95 4.92 4.98 5.05 4.96 4....
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 Spring '14
 Normal subgroup, W. Edwards Deming, A., UCL, LCL, Gandomi

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