| distUnitk | Squared Euclidean distances of the unit k. |
| IB | Spreading measure based on Moran's I index |
| sb_vk | Values v_k to compute the Spatial balance |
| varHAJ | Hajek-Rosen variance estimator |
| wave | Weakly associated vectors sampling |
| wpik | Stratification matrix from inclusion probabilities |
| wpikInv | Stratification matrix from inverse inclusion probabilities |