Sampling efficiency of national, EU and global stratifications

Stratification, dividing the statistical population into less heterogeneous subgroups before sampling, can help improve sampling efficiency by improving representativeness and reducing sampling error. This report explores the added sampling efficiency that is achieved by using the European Environmental stratification for estimating the area covered by the 25 Corine Land Cover (CLC) categories occurring in the semi-natural and managed terrestrial habitats of the wider-countryside. Although the dataset is not ideally suited to assess stratification efficiency for EBONE, the results give some encouragement. The analysis indicates that the pan-European stratification improves sampling efficiency for several land cover categories and performs similar to four more detailed national stratifications, supporting their use as a basis for designing a pan-European biodiversity observation network.