This indicator measures spatial distribution and shows the extent to which the different groups are concentrated in certain political and administrative spatial units (large towns, cantons and larger urban zones). Spatial segregation can serve as an indicator of integration or isolation in society by highlighting the population’s distribution by origin.
The spatial segregation index is less than 0.26 in all the large Swiss towns. Some towns are, however, more homogeneous than others in their distribution by neighbourhood of Swiss nationals and foreign nationals born in Switzerland or born abroad. In Geneva, the indices are very close and are no greater than 0.08. In Bern and Lausanne, foreign nationals from the second or subsequent generations are grouped together in certain neighbourhoods almost twice as much as foreign nationals born abroad (Bern 0.26 compared with 0.14 and Lausanne 0.16 compared with 0.08). In Basel, the indices are close to 0.15 except for Swiss nationals born abroad, who are the most well distributed (0.03).
In Geneva, the segregation index does not show much difference between the different nationality groups. Overall, Swiss nationals and citizens of EU28 and EFTA member countries have similar segregation indices in the neighbourhoods of large towns: in Zurich, they are 0.10 and 0.08 respectively, in Geneva 0.08 and 0.09 and in Lausanne 0.09 and 0.07, etc. People from non-EU and EFTA European countries show the most distorted segregation indices in each of the large towns (0.37 in Bern, 0.29 in Basel, 0.24 in Zurich, 0.23 in Lausanne and 0.11 in Geneva).
The index is lower than 0.25 for citizens of EU-28 and EFTA member countries in all cantons, and is as low as 0.3 and 0.02 in the cantons of Glarus and Basel-Stadt. In fourteen cantons, citizens from non-EU-28 and EFTA member countries show indices equal to or lower than 0.30 (reaching at least 0.4 in Appenzell Innerrhoden and in the canton of Jura). People from continents other than Europe have indices greater than 0.30 in four cantons (Bern, Fribourg, Graubünden and Valais) and 0.40 in two cantons (Jura and Appenzell Innerrhoden). For this nationality group, the lowest index is found in the canton of Glarus, at 0.05).
The segregation index suggested by Duncan and Duncan (1955) measures a group's distribution in spatial units and in theory ranges from 0 (perfectly equal distribution) to 1 (maximum segregation distribution). The index value shows the proportion of the group that would have to be moved to achieve perfectly equal distribution in the observed geographic 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.
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.