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15 Cards in this Set
- Front
- Back
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Statistical Process control |
the application of statistical techniques to ensure that processes meet standards |
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central tendency |
mean |
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control charts |
constructed from historical data, helps distinguish the two types of variation |
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control criteria
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1.no sample points outside the limit 2.points are near the average 3. approx. at even # of points above and below 4. points appear to be randomly distributed around the center line |
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variables |
measures dimensions such as weight, speed, height, or strength falls within an acceptable range use x bar and r chart measured |
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attributes |
good or bad, acceptable or unacceptable does not address degree of failure P chart (percent defectives) or c chart (# of defects) counted |
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xbar charts |
plot of mean of samples taken from a process |
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r chart |
a plot of the range within each sample -difference between highest and lowest numbers |
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sample size vs number of samples |
sample size = 9 boxes number of samples = 12 hrs |
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set control limits |
1. find the mean of all the means 2. select z z=3 for 99.7% or 6 for 99.9997 3. control limit = x barbar +/- z(pop sd) |
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x chart without sigma |
A2 will come from control chart |
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r bar |
find highest sample - lowest sample for each sample and divide by number of samples |
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chart limits for R charts |
D4 and D3 from control chart |
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P chart limits |
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C chart limits |
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