Table 7.Results of Wilcoxon signed-rank test for bias in constituent data for the Quality of Water Service Unit laboratory

[Most probable value, Median bias, and Nearest reporting unit reported in same units as Minimum Reporting Limit; mg/L, milligrams per liter; DIS, dissolved; --, acceptable results; WWR, whole-water recoverable; NEG, negative bias; TITR, electrometric titration; POS, positive bias; mg/L, micrograms per liter; ICP-AES, inductively coupled plasma-atomic emission spectrometry; GF-AAS, graphite furnace-atomic absorption spectrophotometry; IC, ion chromatography; GRAV, gravimetric; ISE, ion-selective electrode; ICP-AES/T, inductively coupled plasma-atomic emission spectrometry, trace; CV-AAS, cold vapor-atomic absorption spectrophotometry; F-AAS, flame-atomic absorption spectrophotometry; LIS, low ionic strength]

Constituent and method of analysis

Most probable value

Number of determinations

Median bias

Nearest reporting unit

p-value

Bias

NUTRIENT CONSTITUENTS

Ammonia as nitrogen (DIS) Minimum Reporting Limit 0.015 mg/L

0.062

4

-0.005

0.01

0.50000

--

0.155

16

-0.005

0.01

0.01440

--

0.266

16

0.004

0.01

0.01657

--

Ammonia plus organic nitrogen as nitrogen (DIS) Minimum Reporting Limit 0.2 mg/L

0.132

4

0.07

0.1

0.12500

--

0.250

16

0.00

0.1

0.84619

--

0.474

16

0.00

0.1

0.58948

--

2.37

5

-0.07

0.1

0.31250

--

Ammonia plus organic nitrogen as nitrogen (WWR) Minimum Reporting Limit 0.2 mg/L

0.132

11

0.07

0.1

0.00098

--

0.250

24

0.01

0.1

0.33103

--

0.474

24

-0.03

0.1

0.19438

--

0.480

3

-0.14

0.1

0.25000

--

2.37

17

-0.07

0.1

0.10536

--

Nitrate plus nitrite as nitrogen (DIS) Minimum Reporting Limit 0.05 mg/L

0.073

4

-0.003

0.01

0.12500

--

0.182

16

-0.012

0.01

0.00003

NEG

0.344

16

-0.004

0.01

0.13696

--

1.72

5

-0.020

0.01

0.75000

--

Orthophosphate as phosphorus (DIS) Minimum Reporting Limit 0.01 mg/L

0.152

8

0.008

0.01

0.29688

--

0.232

8

-0.002

0.01

0.80469

--

Phosphorus as phosphorus (DIS) Minimum Reporting Limit 0.02 mg/L

0.050

4

0.010

0.01

0.25000

--

0.167

16

-0.017

0.01

0.00006

NEG

Phosphorus as phosphorus (WWR) Minimum Reporting Limit 0.01 mg/L

0.050

11

0.010

0.01

0.12500

--

0.167

24

-0.022

0.01

0.00000

NEG

0.223

3

-0.003

0.01

0.25000

--

INORGANIC CONSTITUENTS

Alkalinity (WWR,TITR) Minimum Reporting Limit 1 mg/L

68.5

8

-3.0

1

0.00781

NEG

76.0

12

2.0

1

0.00049

POS

78.5

8

2.1

1

0.00781

POS

106

11

-1.0

1

0.08594

--

107

11

2.6

1

0.00098

POS

130

8

1.8

1

0.06250

--

Aluminum (DIS, ICP-AES) Minimum Reporting Limit 3 mg/L

20.5

8

-1.0

1

0.03906

--

35.7

8

0.4

1

0.43750

--

53.0

7

0.1

1

0.57813

--

Aluminum (WWR, ICP-AES) Minimum Reporting Limit 3 mg/L

20.5

8

3.5

1

0.00781

POS

35.7

8

4.9

1

0.00781

POS

53.0

6

3.6

1

0.03125

POS

Arsenic (WWR, GF-AAS) Minimum Reporting Limit 1 mg/L

2.78

3

0.0

1

1.00000

--

4.05

8

-0.9

1

0.01563

--

5.00

3

-0.6

1

0.25000

--

5.30

6

-0.6

1

0.06250

--

6.04

6

-0.7

1

0.15625

--

7.50

4

-0.2

1

0.37500

--

Barium (DIS, GF-AAS) Minimum Reporting Limit 5 mg/L

11.0

4

0.0

1

0.00000

--

38.5

6

0.0

1

1.00000

--

55.9

5

-0.9

1

0.37500

--

Barium (DIS, ICP-AES) Minimum Reporting Limit 0.2 mg/L

11.0

4

0.0

1

1.00000

--

55.9

3

-0.9

1

0.50000

--

Barium (WWR, ICP-AES) Minimum Reporting Limit 0.2 mg/L

38.5

8

-1.5

1

0.00781

NEG

55.9

8

-2.9

1

0.00781

NEG

67.1

8

-3.1

1

0.00781

NEG

Cadmium (WWR, GF-AAS) Minimum Reporting Limit 1 mg/L

3.75

3

-0.2

1

0.75000

--

7.50

8

0.0

1

0.96875

--

7.68

7

-0.1

1

0.93750

--

25.3

3

-0.3

1

1.00000

--

28.7

8

-1.7

1

0.00781

NEG

37.9

4

-0.9

1

0.62500

--

Calcium (DIS, ICP-AES) Minimum Reporting Limit 0.02 mg/L

12.6

7

0.4

1

0.01563

--

25.4

8

-0.4

1

0.18750

--

30.4

7

-0.4

1

0.48438

--

31.4

12

-0.4

1

0.01123

--

34.7

6

0.8

1

0.68750

--

40.9

8

-0.9

1

0.25781

--

42.0

11

-1.0

1

0.18750

--

53.3

11

-0.3

1

0.19629

--

58.1

8

-0.1

1

0.80469

--

Chloride (DIS, IC) Minimum Reporting Limit 0.1 mg/L

5.35

8

0.35

0.1

0.01563

POS

30.1

8

1.0

1

0.00781

--

38.6

8

1.5

1

0.00781

POS

46.0

12

1.0

1

0.00049

--

48.8

3

0.3

1

0.25000

--

56.7

11

2.3

1

0.00098

POS

60.4

8

1.7

1

0.00781

POS

69.0

8

2.0

1

0.00781

POS

78.5

11

2.5

1

0.00098

POS

85.3

8

1.8

1

0.00781

POS

Chromium (DIS, ICP-AES) Minimum Reporting Limit 1 mg/L

1.94

8

-0.1

1

0.25000

--

11.6

8

-0.6

1

0.01563

--

43.4

8

-1.4

1

0.00781

NEG

Chromium (WWR, ICP-AES) Minimum Reporting Limit 1 mg/L

3.88

6

-0.7

1

0.03125

--

39.5

8

-1.5

1

0.03125

NEG

59.3

10

-1.3

1

0.09570

--

Copper (DIS, ICP-AES) Minimum Reporting Limit 1 mg/L

3.25

8

0.2

1

0.57813

--

15.5

8

0.5

1

0.28906

--

37.5

8

1.5

1

0.00781

POS

Copper (WWR, GF-AAS) Minimum Reporting Limit 1 mg/L

6.50

3

-0.4

1

0.50000

--

31.0

3

-1.0

1

0.50000

--

46.5

4

0.5

1

1.00000

--

Copper (WWR, ICP-AES) Minimum Reporting Limit 1 mg/L

15.5

8

-0.5

1

0.07031

--

37.5

8

0.5

1

0.63281

--

47.0

8

0.0

1

0.09375

--

Dissolved Solids (DIS, GRAV) Minimum Reporting Limit 1 mg/L

219

8

2.8

1

0.06250

--

284

12

9.0

1

0.00098

POS

324

8

7.5

1

0.05469

--

384

11

10.0

1

0.00098

POS

469

11

7.0

1

0.02148

POS

519

8

13.5

1

0.01563

POS

Fluoride (DIS, ISE) Minimum Reporting Limit 0.1 mg/L

0.308

8

-0.01

0.1

0.00781

--

0.421

3

0.08

0.1

0.25000

--

0.520

20

-0.02

0.1

0.21825

--

0.780

8

0.02

0.1

0.00781

--

0.800

11

0.00

0.1

0.00000

--

0.855

8

0.05

0.1

0.79688

--

0.920

8

-0.02

0.1

0.00781

--

1.04

8

-0.04

0.1

0.00781

--

1.14

11

-0.04

0.1

0.82813

--

Iron (DIS, ICP-AES) Minimum Reporting Limit 1 mg/L

1.88

8

1.1

1

0.00781

POS

3.75

6

0.3

1

0.03125

--

5.90

8

-1.9

1

0.00781

NEG

6.70

5

-1.7

1

0.06250

--

37.7

6

2.4

1

1.00000

--

114

8

-4

10

0.00781

--

118

8

-8

10

0.01563

--

150

6

1

10

0.81250

--

171

10

-1

10

0.07422

--

Iron (WWR, ICP-AES) Minimum Reporting Limit 3 mg/L

6.70

6

1.8

1

0.03125

POS

37.7

3

1.4

1

0.25000

--

150

4

1

10

1.00000

--

Iron (WWR, ICP-AES/T) Minimum Reporting Limit 1 mg/L

37.7

3

1.4

1

0.25000

--

150

4

1

10

0.12500

--

Lead (DIS, GF-AAS) Minimum Reporting Limit 1 mg/L

2.24

6

-0.2

1

0.03125

--

51.5

8

-1.5

1

0.39063

--

77.3

10

0.3

1

0.74805

--

Lead (WWR, GF-AAS) Minimum Reporting Limit 1 mg/L

2.24

3

0.8

1

0.25000

--

4.78

7

0.2

1

0.01563

--

6.00

7

0.0

1

0.50000

--

51.5

3

-4.5

1

0.25000

--

54.7

8

-1.2

1

0.31250

--

77.3

4

-0.8

1

0.87500

--

Magnesium (DIS, ICP-AES) Minimum Reporting Limit 0.01 mg/L

2.50

7

0.00

0.1

1.00000

--

6.00

7

0.10

0.1

0.25000

--

6.55

8

-0.15

0.1

0.12500

--

7.65

12

-0.20

0.1

0.00195

NEG

7.74

6

0.01

0.1

0.78125

--

9.12

8

-0.27

0.1

0.00781

NEG

10.6

11

-0.6

1

0.00195

--

12.5

11

-0.5

1

0.00391

--

13.9

8

0.1

1

0.64844

--

Manganese (DIS, ICP-AES) Minimum Reporting Limit 0.2 mg/L

1.20

6

0.05

0.1

0.25000

--

6.80

5

0.00

0.1

0.50000

--

59.0

6

0.5

1

0.25000

--

212

8

-2

10

0.64844

--

261

8

-1

10

0.00781

--

317

10

3

10

0.05859

--

Manganese (WWR, ICP-AES) Minimum Reporting Limit 0.2 mg/L

1.20

3

0.00

0.1

1.00000

--

6.80

7

-0.10

0.1

0.03125

--

59.0

6

-1.5

1

0.06250

--

212

3

-2

10

0.25000

--

261

8

-11

10

0.00781

NEG

317

4

-7

10

0.25000

--

Mercury (WWR, CV-AAS) Minimum Reporting Limit 0.1 mg/L

0.53

3

-0.03

0.1

0.25000

--

0.76

12

-0.01

0.1

0.35742

--

0.93

8

0.02

0.1

1.00000

--

2.27

10

0.03

0.1

0.82617

--

Nickel (DIS, ICP-AES) Minimum Reporting Limit 1 mg/L

3.28

8

0.13

0.1

0.35938

--

15.1

8

-0.1

1

0.64844

--

39.4

8

-0.4

1

0.00781

--

Nickel (WWR, GF-AAS) Minimum Reporting Limit 1 mg/L

6.55

3

-0.5

1

0.25000

--

32.8

3

-1.8

1

0.50000

--

49.2

4

-3.2

1

0.12500

--

Nickel (WWR, ICP-AES) Minimum Reporting Limit 1 mg/L

15.1

8

-1.1

1

0.28906

--

39.4

8

-2.4

1

0.00781

NEG

53.0

8

-2.5

1

0.00781

NEG

Potassium (DIS, F-AAS) Minimum Reporting Limit 0.1 mg/L

0.68

7

-0.08

0.1

0.18750

--

1.85

8

-0.10

0.1

0.14844

--

2.20

8

-0.10

0.1

0.03125

--

2.53

6

-0.03

0.1

0.25000

--

2.75

8

-0.05

0.1

0.17188

--

3.27

12

-0.07

0.1

0.36963

--

4.47

11

-0.07

0.1

0.20703

--

4.77

11

-0.17

0.1

0.16211

--

5.50

8

-0.10

0.1

0.44531

--

Selenium (WWR, GF-AAS) Minimum Reporting Limit 1 mg/L

2.42

3

0.49

0.1

0.25000

--

5.00

3

0.70

0.1

0.50000

--

7.50

3

0.40

0.1

0.50000

--

Silica (DIS, ICP-AES) Minimum Reporting Limit 0.01 mg/L

3.90

8

-0.10

0.1

0.03125

--

6.50

12

-0.20

0.1

0.00049

NEG

7.52

8

0.04

0.1

1.00000

--

9.17

11

-0.17

0.1

0.00098

NEG

11.1

8

-0.1

1

0.00781

--

111.1

11

-0.1

1

0.03711

--

Silver (DIS, GF-AAS, LIS) Minimum Reporting Limit 0.2 mg/L

0.57

3

0.435

0.01

0.25000

--

4.09

6

-0.19

0.1

0.12500

--

6.04

5

0.27

0.1

0.62500

--

Silver (DIS, ICP-AES) Minimum Reporting Limit 1 mg/L

0.57

3

0.4

1

0.25000

--

Silver (WWR, ICP-AES) Minimum Reporting Limit 1 mg/L

4.09

6

-0.3

1

0.09375

--

6.04

4

0.1

1

0.75000

--

7.43

4

0.0

1

0.75000

--

Silver (WWR, ICP-AES/T) Minimum Reporting Limit 1 mg/L

6.04

4

-0.1

1

0.37500

--

7.43

4

0.0

1

0.87500

--

Sodium (AA) Minimum Reporting Limit 0.1 mg/L

22.7

7

-0.7

1

0.46875

--

38.8

8

-0.3

1

0.37500

--

54.0

12

-1.5

1

0.02148

NEG

54.3

8

-1.3

1

0.00781

NEG

60.9

8

-1.9

1

0.01563

NEG

62.0

6

-3.5

1

0.06250

--

71.9

11

-0.9

1

0.17480

--

84.4

11

-2.4

1

0.00098

NEG

96.2

8

-4.7

1

0.00781

NEG

Strontium (DIS, ICP-AES) Minimum Reporting Limit 0.5 mg/L

197

7

3

10

0.68750

--

270

8

-10

10

0.25781

--

498

8

-18

10

0.00781

NEG

Strontium (DIS, ICP-AES/T) Minimum Reporting Limit 0.5 mg/L

23.0

8

0.0

1

0.50000

--

34.5

8

0.5

1

0.26563

--

201

6

-0.5

10

0.37500

--

Strontium (WWR, ICP-AES) Minimum Reporting Limit 0.5 mg/L

92.0

4

-2.0

1

0.12500

--

224

4

-4

10

0.12500

--

279

6

-9

10

0.03125

--

Strontium (WWR, ICP-AES/T) Minimum Reporting Limit 0.5 mg/L

92.0

4

-3.0

1

0.12500

--

224

4

-4

10

0.12500

--

Sulfate (DIS, IC) Minimum Reporting Limit 0.2 mg/L

14.5

8

-0.5

1

0.00781

--

58.5

8

0.5

1

0.00781

--

58.5

3

1.5

1

0.25000

--

59.0

8

1.0

1

0.01563

--

69.0

8

1.5

1

0.03906

POS

75.0

12

1.0

1

0.00098

--

104

11

6

10

0.00391

--

113

8

-3

10

0.64844

--

114

11

6

10

0.00098

--

132

8

-2

10

0.64844

--

Zinc (DIS, ICP-AES) Minimum Reporting Limit 1 mg/L

5.46

8

0.0

1

1.00000

--

29.6

8

5.9

1

0.00781

POS

115

8

6

10

0.00781

--

Zinc (WWR, ICP-AES) Minimum Reporting Limit 1 mg/L

10.0

3

-0.5

1

0.25000

--

30.0

3

0.0

1

1.00000

--

38.5

4

-0.0

1

1.00000

--

48.9

8

0.7

1

0.37500

--

62.8

7

-0.8

1

0.31250

--

134

8

6

10

0.03125

--

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