(Three parts; 16 marks in total) Three replicated water samples were taken at ea
ID: 3045323 • Letter: #
Question
(Three parts; 16 marks in total) Three replicated water samples were taken at each of four locations in a river to determine whether the quantity of dissolved oxygen, a measure of water pollution, varied from one location to another (the lower the dissolved oxygen reading, the higher the level of pollution). Location 1 was adjacent to the waste-water discharge point for a certain industrial plant, and Locations 2, 3, and 4 were downstream sampling points that were 10, 20, and 30 miles from this discharge point. Use the SPSS output in Tables 1-3 to answer the questions in parts (a) and (b). Assume all the required assumptions are satisfied 2. Table 1: ANOVA table comparing all four locations ANOVA Sum of df Between Groups Within Groups Total 36.097 12.032 16.426 001 5.860 41.957 732Explanation / Answer
SPSS used
Descriptives
data
N
Mean
Std. Deviation
Std. Error
95% Confidence Interval for Mean
Minimum
Maximum
Lower Bound
Upper Bound
1.00
3
5.0000
1.00000
.57735
2.5159
7.4841
4.00
6.00
2.00
3
6.0000
.00000
.00000
6.0000
6.0000
6.00
6.00
3.00
3
8.0000
1.00000
.57735
5.5159
10.4841
7.00
9.00
4.00
3
9.0000
1.00000
.57735
6.5159
11.4841
8.00
10.00
Total
12
7.0000
1.80907
.52223
5.8506
8.1494
4.00
10.00
ANOVA
data
Sum of Squares
df
Mean Square
F
Sig.
Between Groups
30.000
3
10.000
13.333
.002
Within Groups
6.000
8
.750
Total
36.000
11
Contrast Coefficients
Contrast
Group
1.00
2.00
3.00
4.00
1
-3
-1
1
3
Contrast Tests
Contrast
Value of Contrast
Std. Error
t
df
Sig. (2-tailed)
data
Assume equal variances
1
14.0000
2.23607
6.261
8
.000
Does not assume equal variances
1
14.0000
2.51661
5.563
4.429
.004
Calculated t=6.261, P=0.000 which is < 0.02 level of significance.
The contrast is significant.
Descriptives
data
N
Mean
Std. Deviation
Std. Error
95% Confidence Interval for Mean
Minimum
Maximum
Lower Bound
Upper Bound
1.00
3
5.0000
1.00000
.57735
2.5159
7.4841
4.00
6.00
2.00
3
6.0000
.00000
.00000
6.0000
6.0000
6.00
6.00
3.00
3
8.0000
1.00000
.57735
5.5159
10.4841
7.00
9.00
4.00
3
9.0000
1.00000
.57735
6.5159
11.4841
8.00
10.00
Total
12
7.0000
1.80907
.52223
5.8506
8.1494
4.00
10.00
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