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Table 3 PPV (%) of approximation methods versus map-based measures for sample areas in Aberdeenshire and Ayrshire

From: The performance of approximations of farm contiguity compared to contiguity defined using detailed geographical information in two sample areas in Scotland: implications for foot-and-mouth disease modelling

   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