Source of covariance	Sum of cross products
Total	${\displaystyle {\sum }_k^P{\displaystyle {\sum }_j^T{\displaystyle {\sum }_i^N\left(\Delta p_{ijk}-\overline{\overline{\overline{\Delta p}}}\right)}}}\left(M_{ijk}-\overline{\overline{\overline{M}}}\right)=$                    (E9)
Average selection effect	$PT{\displaystyle {\sum }_i^N\left(\overline{\overline{\Delta p_i}}-\overline{\overline{\overline{\Delta p}}}\right)}\left(\overline{\overline{M_i}}-\overline{\overline{\overline{M}}}\right)+$
Temporal insurance effect	$P{\displaystyle {\sum }_j^T{\displaystyle {\sum }_i^N\left(\overline{\Delta p_{ij}}-\overline{\overline{\Delta p_i}}\right)}}\left(\overline{M_{ij}}-\overline{\overline{M_i}}\right)+$
Spatial insurance effect	$T{\displaystyle {\sum }_k^P{\displaystyle {\sum }_i^N\left(\overline{\Delta p_{ik}}-\overline{\overline{\Delta p_i}}\right)}}\left(\overline{M_{ik}}-\overline{\overline{M_i}}\right)+$
Spatiotemporal insurance effect	${\displaystyle {\sum }_k^P{\displaystyle {\sum }_j^T{\displaystyle {\sum }_i^N\left(\Delta p_{ijk}-\overline{\Delta p_{ij}}-\overline{\Delta p_{ik}}+\overline{\overline{\Delta p_i}}+\overline{\overline{\overline{\Delta p}}}\right)}}}\left(M_{ijk}-\overline{M_{ij}}-\overline{M_{ik}}+\overline{\overline{M_i}}+\overline{\overline{\overline{M}}}\right)$