Figure 4

The relative difference, \(\delta _{ij}=(D_{ij}-\bar{D}_{ij})/\bar{D}_{ij}\) with time-cohorts. The sum of elements i, j over all classes equals zero. The value \(-1\) appears often because it corresponds to \(D_{ij}=0\).

The relative difference, \(\delta _{ij}=(D_{ij}-\bar{D}_{ij})/\bar{D}_{ij}\) with time-cohorts. The sum of elements i, j over all classes equals zero. The value \(-1\) appears often because it corresponds to \(D_{ij}=0\).