Table 3 PPV (%) of approximation methods versus map-based measures for sample areas in Aberdeenshire and Ayrshire
Current method | |||||||||
|---|---|---|---|---|---|---|---|---|---|
All premises <1 km point distance | All premises <3 km point distance | All premises <5 km point distance | All premises <26 m field distance | All premises <151 m field distance | All premises <1 km field distance | By Voronoi tessellation | By area weighted tessellation | ||
Aberdeenshire | |||||||||
Gold standard | All <15 m | 65.2 | 22.7 | 10.4 | 93.9 | 85.0 | 37.4 | 38.1 | 36.4 |
All <15 m - river | 62.3 | 21.4 | 9.9 | 87.7 | 79.4 | 35.0 | 35.7 | 34.1 | |
All <15 m - road | 55.1 | 19.6 | 8.9 | 79.8 | 72.2 | 31.8 | 32.3 | 31.2 | |
All <15 m - river/road | 52.2 | 18.3 | 8.3 | 73.6 | 66.7 | 29.3 | 29.9 | 28.9 | |
All <15 m - river/road/ditch | 49.3 | 16.5 | 7.5 | 66.9 | 60.6 | 26.7 | 26.9 | 26.3 | |
All <15 m - river/ditch | 59.4 | 18.9 | 8.8 | 78.5 | 71.1 | 31.3 | 31.6 | 30.6 | |
Shared fence | 52.2 | 18.4 | 8.4 | 74.8 | 67.8 | 29.8 | 31.3 | 29.8 | |
Shared fence - river | 50.7 | 17.8 | 8.1 | 72.4 | 65.6 | 28.9 | 29.9 | 28.6 | |
Shared fence - river/ditch | 49.3 | 16.2 | 7.4 | 66.3 | 60.0 | 26.4 | 27.2 | 26.3 | |
Ayrshire | |||||||||
Gold standard | All <15 m | 56.7 | 17.2 | 7.4 | 96.1 | 80.4 | 32.0 | 41.2 | 39.1 |
All <15 m - river | 53.2 | 15.8 | 6.8 | 89.0 | 74.4 | 29.6 | 38.0 | 36.1 | |
All <15 m - road | 48.3 | 15.0 | 6.4 | 82.9 | 69.3 | 27.5 | 36.5 | 34.6 | |
All <15 m - river/road | 44.8 | 13.6 | 5.9 | 75.7 | 63.3 | 25.2 | 33.3 | 31.6 | |
All <15 m - river/road/ditch | 43.8 | 12.4 | 5.3 | 68.5 | 57.3 | 22.8 | 30.4 | 28.5 | |
All <15 m - river/ditch | 52.2 | 14.5 | 6.3 | 81.5 | 68.1 | 27.1 | 35.2 | 33.1 | |
Shared fence | 46.3 | 14.1 | 6.0 | 78.2 | 65.4 | 26.0 | 33.5 | 31.9 | |
Shared fence - river | 44.3 | 13.1 | 5.7 | 73.5 | 61.4 | 24.4 | 31.8 | 30.2 | |
Shared fence - river/ditch | 43.3 | 12.0 | 5.2 | 66.9 | 55.9 | 22.2 | 29.3 | 27.5 | |