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Table 2 Correlation coefficients between measured PCE concentrations in water samples and model-generated estimates

From: Evaluation of the Webler-Brown model for estimating tetrachloroethylene exposure from vinyl-lined asbestos-cement pipes

  No. of Samples Spearman Correlation Coefficient P-Value
All Samples 88 0.48 < 0.001
According to:    
Complexity of pipe configurationa    
   Simple 31 0.51 0.003
   Complex 57 0.38 0.003
Magnitude of flowa    
   High (> 19 homes) 19 0.37 0.1
   Medium (3–19 homes) 33 0.30 0.09
   Low (< = 2 homes) 36 0.54 0.0007
Position along pipea    
   End 44 0.44 0.003
   Beginning/Middle 44 0.44 0.003
Overestimated housing densitya    
   Yes 25 0.52 0.008
   No 63 0.47 0.0001
Season sampleda    
   Spring 74 0.50 < 0.0001
   Autumn 14 0.58 0.03
Water fixture sampleda    
   Tap or spigot 10 0.84 0.002
   Hydrant 18 0.34 0.2
   Unknown 60 0.38 0.003
Sampling personnela    
   Sampler 1 69 0.45 0.0001
   Sampler 2 18 0.57 0.01
   Sampler 3 1 ---b ---b
Towna    
   Barnstable 7 ---c ---c
   Bourne 16 0.53 0.03
   Brewster 7 0.018 1.0
   Chatham 6 0.39 0.4
   Falmouth 6 0.49 0.3
   Provincetown 5 ---c ---c
   Sandwich 9 0.53 0.1
   Plymouth 25 0.56 0.003
   Wareham 7 0.48 0.3
Pipe installation yeara    
   1968–1972 23 0.42 0.05
   1973–1976 32 0.56 0.0008
   1977–1980 33 0.37 0.03
  1. a See text for definitions and further description.
  2. b Analyses were not conducted because of the small sample size.
  3. c Analyses were not conducted because all water samples had undetectable PCE levels.