Conductivity is one of many properties measured to evaluate water quality. The table below (also attached as an Excel file) contains conductivity measurements (µS/cm) of groundwater samples from a single well.
First, prepare a graph of the raw data.
Then set up estimates of the conductivity
Also develop a 95% tolerance interval estimate of the conductivity that will include 99% of the conductivities.
Finally, prepare a table that presents your estimates in a tabulated form.
Your submission should take the form of a word document that includes the graph, the table of estimates, and your calculations.
Conductivity |
Week |
1220 |
1 |
1130 |
2 |
1400 |
3 |
1400 |
4 |
1625 |
5 |
1670 |
6 |
2100 |
7 |
1070 |
8 |
1622 |
9 |
1680 |
10 |
1900 |
11 |
1700 |
12 |
1600 |
13 |
1580 |
14 |
1620 |
15 |
1700 |
16 |
1840 |
17 |
1772 |
18 |
1325 |
19 |
1150 |
20 |
1300 |
21 |
1400 |
22 |
1360 |
23 |
1340 |
24 |
1250 |
25 |
1360 |
26 |
1417 |
27 |
1810 |
28 |
1700 |
29 |
1725 |
30 |
1500 |
31 |
1725 |
32 |
1700 |
33 |
2000 |
34 |
1900 |
35 |
2040 |
36 |
970 |
37 |
1150 |
38 |
1100 |
39 |
1010 |
40 |
880 |
41 |
975 |
42 |
1300 |
43 |
1050 |
44 |
1116 |
45 |
1350 |
46 |
1350 |
47 |
1250 |
48 |
1250 |
49 |
1300 |
50 |
1230 |
51 |
1250 |
52 |
1130 |
53 |
1300 |
54 |
First, prepare a graph of the raw data.
Conductivity | |
count | 54 |
mean | 1,436.89 |
sample standard deviation | 301.24 |
population average (95% CI),
confidence interval 95.% lower | 1,356.54 |
confidence interval 95.% upper | 1,517.23 |
population standard deviation (95% CI), and
a future individual measurement (95% PI).
Predicted values for: Conductivity | ||||||
95% Confidence Interval | 95% Prediction Interval | |||||
Week | Predicted | lower | upper | lower | upper | Leverage |
55 | 1,237.964 | 1,082.021 | 1,393.908 | 651.805 | 1,824.123 | 0.076 |
Also develop a 95% tolerance interval estimate of the conductivity that will include 99% of the conductivities.
tolerance interval 95.% lower | 846.48 |
tolerance interval 95.% upper | 2,027.30 |
half-width | 590.41 |
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