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Table 1 Accuracy of three food retail outlet lists, as compared with ground-truthing

From: Modified ground-truthing: an accurate and cost-effective food environment validation method for town and rural areas

   List 1: Business Analyst (BA) List 2: Modified ground-truthing,a (stores outside of clusters assumed open) List 3: Modified ground truthing,a (stores outside of clusters assumed closed)
   Site   Site   Site  
   A B C Total A B C Total A B C Total
Stores on list for comparison with traditional ground-truthing 14 74 63 151 15 78 60 153 14 66 46 126
True positives stores correctly listed 7 48 35 90 14 69 49 132 14 66 46 126
False positives stores that should not have been on the list 7 26 28 61 1 9 11 21 0 0 0 0
False negatives stores missing from the list 7 24 15 46 0 3 1 4 0 6 4 10
      Mean     Mean     Mean
Positive Predictive Value (PPV) true positives/(true positives + false positives) 0.50 0.65 0.56 0.57 0.93 0.88 0.82 0.88 1.00 1.00 1.00 1.00
Sensitivity true positives/(true positives + false negatives) 0.50 0.67 0.70 0.62 1.00 0.96 0.98 0.98 1.00 0.92 0.92 0.95
  1. aThe list of stores derived from driving only the streets within 1/8 mile buffer of any two stores on the commercial list