A comparison of the predictive abilities of four approaches for modelling the distribution of cetaceans

5 Introduction Background 6 Comparison of predictive ability between modelling techniques 9 ‘False’ Absences 11 Study area 11 The harbour porpoise (Phocoena phocoena) 12 Materials and Methods Data collection 13 Estimating position of sightings 14 Track and surveyed grid cells 14 Presence and Absence cells 15 Data partitioning 16 Ecogeographic data 16 1) PCA-based technique 17 PCA-intra-model evaluation 18 2) Ecological Niche-Factor Analysis (ENFA) 18 ENFA Intra-Model Evaluation 19 3) Genetic Algorithm for Rule-set Prediction (GARP) 20 GARP Intra-model evaluation 21 4) Generalised Linear Modelling (GLM) 21 Inter-model Evaluation 22 Presence-absence thresholds 22 Results Sightings 24 1) PCA-based technique 26 2) Ecological Niche Factor Analysis 29 3) Genetic Algorithm for Rule-set Prediction (GARP) 32