the level of delivery risk mitigation offered by replacement ratios is contingent upon the correlation between the biodiversity outcomes at offset sites in reality biodiversity outcomes are often closely correlated so it is difficult to eliminate delivery risk using replacement ratios creating offsets using different ecological restoration techniques or dispersing offset sites across space may contribute relatively more to delivery risk mitigation moilanen et al the party liable for the delivery risk purchases insurance or a similar product against the possibility that the offset site fails to deliver the required biodiversity outcomes