Where and How Do Swiss and Foreigners Live? Segregation in the Geneva and Zurich Housing Markets
ever, maps will describe the spatial distribution of the groups in the regions under study.
The evenness dimension of residential segregation refers to the distribution of one (or more) social group across the different sub-areas of a region and measures the degree of overrepresentation (underrepresentation) of this group in the region’s sub- areas. Evenness is maximized when all sub-areas in the region have the same relative number of the different social groups as the region as a whole, and is minimized when no members of the different social groups share a common residential sub-area. Note that the measures of evenness depend on the relative size of the groups being compared. In this paper, we calculate the index of dissimilarity originally proposed by Duncan and Duncan (1955) and subsequently applied in the literature by e. g. Wong (2008). This index can be used to measure the residential distribution of a single group against the rest of the population, or of one group against another, according to the following formulas:
x IDx =
ti − xi T −X
x IDy =
w h e r e t i i s t h e p o p u l a t i o n s i z e i n s u b - a r e a i ; x i i s t h e p o p u l a t i o n o f g r o u p X m e m b e r s i n s u b - a r e a i ; y i r e p r e s e n t s t h e p o p u l a t i o n o f g r o u p Y m e m b e r sub-area i; T represents the population size in the region; X is the population of group X members in the region; and Y represents the population of group Y members in the region. s i n
The dissimilarity index varies between 0 (complete evenness) and 100 (complete u n e v e n n e s s ) . I n t h e s i n g l e g r o u p c a s e ( x I D x ) , e q u a t i o n ( 1 ) , t h e i n d e x r e p r e s e n t s t h proportion of group X member that would have to shift location in order to achieve complete evenness. As reported in Table 1, this means that, for instance, 17.6% of the foreigners with low education level would have to move across districts in order to have complete evenness in their distribution in Geneva (20.2% in Zurich). The e t w o - g r o u p i n d e x ( x I D y ) , e q u a t i o n ( 2 ) , c a l c u l a t e s t h e e v e n n e s s d i s t r i b u t i o n b e t w e e n t w o d i f f e r e n t p o p u l a t i o n g r o u p s .
It should be noted that comparisons of calculated segregation indices be- tween different regions or cities may lead to different conclusions depending on the aggregation level of the data. Indeed, results obtained at a given geographical level may not hold for another geographical aggregation (see Wong, 2004). This phenomenon is referred to the so-called modifiable areal unit problem (MAUP). However, comparing the results in Table 1, we observe that, both in Geneva and