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ENMA 420-520 Lecture 10 Slides

# ENMA 420-520 Lecture 10 Slides - Statistical Concepts for...

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Click to edit Master subtitle style 10/17/09 Statistical Concepts for Engineering Management ENMA 420 / 520 Lecture #10 Statistical Process and Quality Control 11

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10/17/09 Total Quality Management A management approach for an organization, centered on quality, based on the participation of all its members and aiming at long-term success through customer satisfaction, and benefits to all members of the organization and to society. (ISO 8402:1994) 22
10/17/09 Total Quality Management (Cont’d) Components: Concepts Customer focused, process oriented, data- enabled Systems Focus on entities, relationships & boundaries Tools Flowcharts, cause-and-effect diagrams, statistical process control charts 33

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10/17/09 Variable Control Charts A plot of variable measurements periodically (typically over time) Goal is to separate out two types of variation: Due to assignable causes Due to random variation A process is said to be in control when the quality characteristics are subject only to random variation. 44
10/17/09 Variable Control Charts (Cont’d) Examples: Centerline of the mean Upper and lower control limits of +/- 3s Caution: Control charts are for processes that are in control Can be applied to future data only when 55

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10/17/09 Exercise 16.2 66 CARBPCT Mean 3.430909091 Standard Error 0.034494081 Median 3.48 Mode 3.5 Standard Deviation 0.198153407 Sample Variance 0.039264773 Kurtosis 0.785933604 Skewness -0.731914277 Range 0.88 Minimum 2.9 Maximum 3.78 Sum 113.22 Count 33 Confidence Level(95.0%) 0.070262143 LCL = 2.83644887 UCL = 4.025369312
10/17/09 Exercise 16.2 (Cont’d) 77 0 2 4 6 8 10 12 2 3 4 5 6 7 8 9 10 11

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10/17/09 Control Charts for Means Establishes center line (mean) and lower/upper control limits Standard deviation of process estimated using data collected while process is in control Past practice includes estimating process σ using the range and a parameter based on sample size and 88
10/17/09 Control Charts for Means (Cont’d) 99 Locationof Center LineandControl Limitsfor anl ҧ - chart ° °°°°° H ±h » : - Ӗ = σ l ҧ l l l = 1 l UCL : - Ӗ + - 2 l l LCL : - Ӗ − - 2 l l w : here - = Number of samples , each of size - - ҧ l = Sample mean for the - th sample - - = Range of the - th sample - - = σ l l l l = 1 l And A 2 . isdeterminefromtheappropriatetables ( > ) , For largesamples n 15 collectedfromaprocesswithnotimetrend theUCL andLCL maybe : computer by UCL : - Ӗ + 3l / ξ l LCL : - Ӗ 3l / ξ l w here sisthestandard deviationof all nk . samplemeasurements

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10/17/09 Control Charts for Means (Cont’d)
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