Page 276 - Statistics for Environmental Engineers

L1592_Frame_C30 Page 279 Tuesday, December 18, 2001 2:49 PM

y ln( y)
X 1 X 2 X 3
−1 1 −1 1.88 0.631
−1 −1 −1 2.1 0.742
−1 1 1 6.1 1.808
−1 −1 1 6.4 1.856
1 −1 −1 16 2.773
1 1 −1 17 2.833
1 −1 1 19 2.944
1 1 1 19.5 2.970
0 0 0 10.1 2.313
0 0 0 10.1 2.313
0 0 0 10.5 2.351
0 0 0 10.9 2.389
Note: X 1 is the type of wastewater:
−1 = influent +1 = effluent
X 2 is preservative: −1 = none +1 = added
X 3 is method: −1 = Method A +1 = Method B

30.2 Fly Ash Density. The 16 runs in the table below are from a study on the effect of water
content (W), compaction effort (C), and time of curing (T) on the density of a material made
from pozzolanic fly ash and sand. Two runs were botched so the effects and interactions must
be calculated by regression. Do this and report your analysis.

Factor Density
3
Run W C T (lb/ft )
1 − − − 107.3
2 + − − Missing
3 − + − 115.9
4 + + − 121.4
5 − − + 101.8
6 + − + 115.6
7 − + + 109.3
8 + + + 121.1
9 − − − Missing
10 + − − 120.8
11 − + − 118.6
12 + + − 126.5
13 − − + 99.8
14 + − + 117.5
15 − + + 107.6
16 + + + 118.9

30.3 Metal Inhibition. Solve Exercise 27.5 using regression.

© 2002 By CRC Press LLC