This indicator provides information on the spatial distribution of different population groups. It measures the concentration, or the dispersion, with which persons belonging to these groups are distributed in different spatial units.
From an integration perspective, a decrease in the spatial dissimilarity index indicates an improved situation.
Since 2011, the spatial dissimilarity index in Zurich has decreased among persons born in Switzerland with foreign or the Swiss nationality, whereas it has slightly increased among Swiss nationals born abroad. In Geneva, it has decreased among foreign nationals born in Switzerland and Swiss nationals born abroad and has increased in the two other groups. In Basel and Lausanne, the spatial dissimilarity index has decreased across all groups with the exception of Swiss nationals born abroad in Lausanne. In Bern the opposite is observed.
The spatial dissimilarity index developed by Duncan and Duncan measures a group's distribution in spatial units and in theory ranges from 0 (perfectly even distribution) to 1 (maximum segregation distribution). The index value shows the proportion of the group that would have to be moved to achieve perfectly even distribution in the observed geographic area.
The index is calculated as follows:
With ti = Total population in the spatial unit i; T = Total population in observed area; pi = proportion of group in spatial unit i; P = proportion of the group in observed area; xi = proportion of group X in spatial unit i; X = population from group X in observed area; n= Number of spatial units in observed area.
The political and administrative spatial sub-units on which the calculations are based are neighbourhoods in large towns and communes for cantons and larger urban zones.
