Page 106 - Statistics for Environmental Engineers

L1592_Frame_C11 Page 101 Tuesday, December 18, 2001 1:47 PM

can be improved. Precision can be increased. Bias can be reduced. Lab throughput can be increased
while precision and bias remain in control. Strive for quality assurance and quality improvement.

References

Johnson, R. A. (2000). Probability and Statistics for Engineers, 6th ed., Englewood Cliffs, NJ, Prentice-Hall.
Kateman, G. and L. Buydens (1993). Quality Control in Analytical Chemistry, 2nd ed., New York, John Wiley.
Miller, J. C. and J. N. Miller (1984). Statistics for Analytical Chemistry, Chichester, England, Ellis Horwood Ltd.
Tiao, George, et al., Eds. (2000). Box on Quality and Discovery with Design, Control, and Robustness, New
York, John Wiley & Sons.

Exercises

11.1 Glucose BOD Standards. The data below are 15 paired measurements on a standard glu-
cose/glutamate mixture that has a theoretical BOD of 200 mg/L. Use these data to construct
a Range chart and an X chart.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
203 213 223 205 209 200 200 196 201 206 192 206 185 199 201
206 196 214 189 205 201 226 207 214 210 207 188 199 198 200

11.2 BOD Range Chart. Use the Range chart developed in Exercise 11.1 to assess the precision
of the paired BOD data given in Exercise 6.2.

© 2002 By CRC Press LLC