1. Petrochemical Industry
We will plot a control chart for a chemical used
as a catalyst in the manufacturing of a
polyester precursor.
• Create a control standard of a known
concentration.
• Analyze it numerous times on the same
analytical instrument.
• treat the data statistically.

2. Data for Cobalt Control Standard
Date Cobalt, ppm target Date Cobalt, ppm
500 ppm
06/04/04 484 08/03/04 504
06/08/04 502 08/07/04 511
06/12/04 502 08/11/04 525
06/16/04 511 08/15/04 532
06/20/04 511 08/19/04 529
06/24/04 541 08/23/04 541
06/28/04 538 08/27/04 512
07/02/04 506 08/31/04 509
07/06/04 492 09/04/04 516
07/10/04 497 09/08/04 516
07/14/04 501 09/12/04 513
07/18/04 510 09/16/04 485
07/22/04 520 09/20/04 521
07/26/04 529 09/24/04 526

3. Statistics for Control Chart
limits key Cobalt
_KSigma 2
_Alpha 0.04550
_Std Dev 10.63472
_Range Span 2
_Mean 514.66666
_LCL 493.39722
_UCL 535.936113

4. Control Chart
Individual Measurement of Cobalt
560
550
540
530 UCL=535.94
520
Cobalt Avg=514.67
ppm 510
500
LCL=493.40
490
480
470
06/12 06/24 07/06 07/18 07/30 08/11 08/23 09/04 09/16 09/28

5. Interpret Chart for Patterns*
interpret control chart for patterns.
• note instability patterns on catalyst chart;
• erratic data fluctuations which are too wide
for the control limits, and for this process it is
most likely caused by:
• instrument problems, contaminants in the
control standard sample.
• Engineer will run process samples off the line

6. Service Sector
Control chart application to computer hardware
dispatch hours for a company.
Graph hours per week for hardware service
calls nationwide.
Moving averages graphed.

7. Dispatch Data
Week Hours
09-Oct 4831.95 UCL 8885
16-Oct 6873.05 LCL 2812
23-Oct 7320.46 Mean 5848
30-Oct 7125.05 KSigma 3
06-Nov 5240.30
13-Nov 6032.35
20-Nov 5965.87
27-Nov 3398.82
04-Dec 5568.26
11-Dec 4797.87
18-Dec 5492.55
25-Dec 3487.23
01-Jan 2563.78
08-Jan 4519.24
15-Jan 5512.70

9. Interpret Control Chart*
Interpret control chart pattern
• cycles-short trends that repeat a pattern
over a long enough period of time
• see hours are down based on time of year:
holidays
• has shown outliners when new processing
code was installed with errors.