Table 1.
Accuracy of three food retail outlet lists, as compared with ground-truthing
| 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 |
aThe list of stores derived from driving only the streets within 1/8 mile buffer of any two stores on the commercial list