Page 116 - Statistics for Environmental Engineers

L1592_frame_C12.fm Page 112 Tuesday, December 18, 2001 1:48 PM

12.2 Charting. Use the first 20 duplicate observations in the data set below to construct Shewhart,
Range, and Cusum charts. Plot the next ten observations and decide whether the process has
remained in control. Compare the purpose and performance of the three charts.

Observ. y 1 y 2 Observ. y 1 y 2
1 5.88 5.61 16 5.70 5.96
2 5.64 5.63 17 4.90 5.65
3 5.09 5.12 18 5.40 6.71
4 6.04 5.36 19 5.32 5.67
5 4.66 5.24 20 4.86 4.34
6 5.58 4.50 21 6.01 5.57
7 6.07 5.41 22 5.55 5.55
8 5.31 6.30 23 5.44 6.40
9 5.48 5.83 24 5.05 5.72
10 6.63 5.23 25 6.04 4.62
11 5.28 5.91 26 5.63 4.62
12 5.97 5.81 27 5.67 5.70
13 5.82 5.19 28 6.33 6.58
14 5.74 5.41 29 5.94 5.94
15 5.97 6.60 30 6.68 6.09

12.3 Moving Averages. Use the first 20 duplicate observations in the Exercise 12.2 data set to
construct an MA(4) moving average chart and an EWMA chart for λ = 0.6. Plot the next ten
observations and decide whether the process has remained in control. Compare the purpose
and performance of the charts.

© 2002 By CRC Press LLC