Testing for geographic scope and scale effects with choice modelling: Application to the Great Barrier Reef

The focus of this report is to report choice modelling experiments that have tested the consistency of values across differently scoped dimensions of an environmental asset. The case study involved the Great Barrier Reef (GBR) in Australia, where a key policy question is to identify if protection values for one part of the reef can be transferred to different sections and scaled from local case studies to the whole reef area without adjustment. The study involved 12 split-samples in three CM experiments to assess values for the whole GBR, a regional section of the GBR and a local reef area while controlling for variations across populations, the scope of the choice tasks, and survey formats. The results demonstrate that issues of geographic scope and scale remain challenging in CM experiments. Contrary to expectations, the proportional values for different regions of the GBR remained consistent when geographic scope and scale increased, while absolute values declined. This was despite substantial efforts in designing and presenting the surveys to define the amenity of interest to respondents. The results indicate that it is difficult to identify single unit values for an environmental amenity that can be easily transferred and extrapolated across geographic regions and scales. However, there may be good theoretical reasons why marginal values for specific areas of interest in the GBR have much higher protection values, which then decline as larger and more general areas are considered.