Residential segregation refers to the disproportionate distribution of population groups across a geographical area. Groups can be segregated on the basis of any characteristic (such as occupation, income, religion, age or ethnicity) and at any geographical scale. In most cases, segregation is, however, measured with regard to residential areas of a city. The extent of the unequal distribution of selected characteristics can be expressed by different statistical measures. Sociologists, economists and demographers have long studied how social groups tend to be differentiated in residential space and developed a broad range of explanations. As a consequence, segregation has been explained by a variety of theories, which are discussed in this paper. The topics examined by empirical research include temporal dynamics, geographical patterns, societal causes and effects on life chances. This entry focuses on major conceptual facts regarding residential segregation and only marginally discusses the methodological issues connected with its measurement.
Segregation refers to nothing more than the “disproportionate distribution of population groups across urban sub-units”
[1] (p. 217). It can be conceived very abstractly as the unequal distribution of “elements over subunits of a unit” (ibid.). “Elements” can be occupational or income groups, as well as religious groups, age groups, or people of a certain origin. “Sub-units” are usually residential areas of the “unit” city.
Issues of residential segregation have been studied on an international scale. They have been subject to longstanding political and theoretical debates and form an inter- and transdisciplinary field of study. Residential segregation includes various dimensions and domains, and a range of methods has been developed for measuring segregation.
The extent of the unequal distribution of the described characteristics can thus be expressed by different statistical measures. The segregation index
[2], which measures the distribution of a population group in relation to the total population, is particularly frequently used in research. The index can take values between 0 and 100 and indicates the proportion of a population group that would have to move in order to achieve an equal distribution across the city. A value of 0 stands for a completely even distribution of the examined characteristic, and a value of 100 for complete spatial separation. However, great caution must be exercised when interpreting index values
[3] since they depend strongly on the underlying division of the city as a whole into subareas. The larger the subareas, the more likely they are to contain different population groups and the lower the segregation index. In addition, there are different characteristics of urban areas (e.g., building density, physical conditions and building types). For this reason, the comparability of segregation indices between different cities is very limited.
Over the past 100 years, various approaches have been developed to explain segregation. Essentially, six currents can be distinguished.
Encyclopedia
