#33 Babita
Turbid water is muddy or cloudy water. Sunlight is necessary formost life forms; thus turbid water is considered a threat towetland ecosystems. Passive filtration systems are commonly used toreduce turbidity in wetlands. Suspended solids are measured inmg/l. Is there a relation between input and output turbidity for apassive filtration system and, if so, is it statisticallysignificant? At a wetlands environment in Illinois, the inlet andoutlet turbidity of a passive filtration system have been measured.A random sample of measurements are shown below. (Reference:EPA Wetland Case Studies.)
| Reading | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Inlet(mg/l) | 88.5 | 58.5 | 69.8 | 58.0 | 80.4 | 20.2 | 18.4 | 63.6 | 91.5 | 55.7 | 70.5 | 90.5 |
| Outlet(mg/l) | 9.9 | 4.2 | 13.4 | 5.8 | 9.4 | 4.8 | 3.2 | 10.5 | 16.1 | 3.5 | 7.6 | 14.5 |
Use a 1% level of significance to test the claim that there is amonotone relationship (either way) between the ranks of the inletreadings and outlet readings.
(a) Rank-order the inlet readings using 1 as the largest datavalue. Also rank-order the outlet readings using 1 as the largestdata value. Then construct a table of ranks to be used for aSpearman rank correlation test.
| Reading | Inlet
Rank x | Oulet
Rank y | d = x -y | d2 |
1
2
3
4
5
6
7
8
9
10
11
12
|
|
|
|
Σd2 = |
(c) Compute the sample test statistic. (Use 3 decimalplaces.)
