Residential
segregation
Summary of measures provided by Dolores Acevedo-Garcia,
Kimberly Lochner, and Ichiro Kawachi to the Social Environment working group. Last
revised December, 2001.
Table of Contents
a. Measurement Approaches
b. References
Measurement Approaches
The table below provides an overview of approaches for measuring residential segregation,
poverty concentration and related concepts in sociological literature.
|
|
|
|
| Metropolitan area economy |
| Metropolitan area mean income |
Average household income |
(Jargowsky, 1997) |
| Metropolitan area income
inequality |
Coefficient of variation of the
household distribution of income, i.e. standard deviation of household income divided by
mean household income |
(Jarkowsky, 1997) |
|
|
|
| Geographic concentration of
poverty |
| MA poverty rate |
% of total number of MA persons
that is poor (below federal poverty line) |
(Massey and Denton, 1993) |
| High poverty neighborhood |
Neighborhood where poverty rate³ 40% |
(Jargowsky, 1997) |
| Neighborhood poverty rate (NPR) |
% of MA total population that
resides in high-poverty neighborhoods |
(Jargowsky, 1997) |
| Concentration of poverty
(affluence) |
% of MA poor (affluent)
population that resides in high poverty (affluence) neighborhoods |
(Jargowsky, 1997; Waitzman
and Smith, 1998) |
| Poverty concentration |
Exposure to poverty across
neighborhoods (based on isolation index) For a given MA (j) and a
racial/ethnic group (m), the index of exposure to poverty (EPjm),
is given by
where xi jm, ti j and Xjm
are the number of members of the group m in census tract i, the total
population of census tract i, and the number of members of the minority group m
for the entire MA j; eji is the number of persons living in
poverty; N is the total number of census tracts in MA j. For example, EPjm
= 0.15 indicates that in MA j, the typical member of group m lives in a
census tract where 15% of the population lives in poverty. |
(Massey and Denton, 1993) |
|
|
|
| Residential segregation by
race/ethnicity |
| Dissimilarity |
The dissimilarity index (D),
which may be interpreted as the proportion of the minority racial/ethnic group of interest
(m) that would need to move across sub-units in order to achieve an even
distribution, is given by 
where ti and xi are the total population and
minority proportion of areal sub-unit (i.e. census tract) i, and T and X are
the population size and minority proportion of the whole geographic area, i.e. MA ( j),
which is subdivided into N areal sub-units.
Ranges from 0, no residential segregation, to 1, complete residential segregation. |
(Massey and Denton, 1988) |
| Isolation |
The isolation index (P),
which measures the extent to which a member of a racial/ethnic group (m) is likely
to be in contact with members of this same group (as opposed to members of other groups),
is given by 
where x, X and t are defined as above; e.g. Pjm=0.6
indicates that in MA j, the average member of group m lives in a census
tract where the probability that (s)he will have contact with another member of group
m is 0.6.
Ranges from the overall proportion minority in the entire MA, no residential
segregation, to 1, complete residential segregation. |
(Massey and Denton, 1988) |
|
|
|
| Concentration |
Concentration refers to the
relative space occupied by a minority group in a geographic area. If a group occupies a
small share of the total area, it is said to be residentially concentrated. A simple
concentration index (C) can be derived from an application of the dissimilarity
index defined above 
where xi and Xi are defined as before; and ai
equals the land area of sub-unit i and A is the total land area of the
geographic area (i.e. MA) j. This index may be interpreted as the share of minority
members that would have to move across sub-units in order to achieve a uniform density of
minority members over all units.
Ranges from 0, no residential segregation, to 1, complete residential segregation.
Massey and Denton have proposed two more complex indices of concentration (the absolute
concentration index, ACO, and the relative concentration index, RCO). |
(Massey and Denton, 1988) |
|
|
|
| Centralization |
Centralization refers to nearness
to the center of the urban area, which in the largest and oldest US MAs is often
characterized by dilapidated housing and socioeconomic deprivation. The absolute
centralization index is given by 
where the N areal sub-units are ordered by increasing distance from the central
business district, C is the cumulative proportion of X in sub-unit i,
and A is the cumulative proportion of land area through sub-unit i.
Ranges from 1 to -1. Positive values in indicate tendency of group X to live close to
the center of the MA; negative values indicate tendency to live in the outlying areas; 0
denotes a uniform distribution throughout the MA. |
(Massey and Denton, 1988) |
|
|
|
| Clustering |
Clustering is the extent to which
areal sub-units inhabited by minority members adjoin one another, or cluster, in space.
The preferred measure of this dimension is the index of spatial proximity (SP)
given by the average of intergroup proximities (Pxx, Pyy) 
where T, X and Y are the population size, minority proportion, and
majority proportion of the whole geographic area. To illustrate, the measure of spatial
proximity for group X, i.e. the average proximity between members of group X,
is given by
where cij represents a distance function between areas i and j;
and x and X are defined as before.
SP equals 1, when there is no differential clustering between X and Y,
and is greater than 1 when members of each group live closer to one another than to each
other. |
(Massey and Denton, 1988) |
|
|
|
| Residential segregation by
class |
| Neighborhood sorting index (NSI)
and Neighborhood distribution of income |
 where  is the standard deviation of the neighborhood income
distribution and  is the
standard deviation of the household income distribution. The neighborhood distribution of
income is the distribution of households by the mean household income of the neighborhood
in which they live--each neighborhood is weighted by the number of household it contains.
The household distribution of income is the distribution of households by their own
income. If there was no income segregation, all neighborhoods would have the same mean
income and , and
thus NSI, would be zero. At the other extreme, if there was perfect income segregation,
all households would live in neighborhoods where the mean income approximates their own.
In this case, would approach , and thus NSI would
approach 1.
NSI2 is the proportion of the total variance in household income among
rather than within neighborhoods |
(Jargowsky, 1997) |
| Dissimilarity of the poor
(affluent)1 |
Proportion of poor (affluent)
families that would have to move in order to achieve an even socioeconomic distribution
throughout the metropolitan area. See dissimilarity index above
Thresholds:
Poor: below federal poverty line
Affluent: $75,000 (top 12% of the 1989 family income distribution) |
(Waitzman and Smith, 1998) |
|
|
|
| Isolation of the poor (affluent)1 |
Exposure to poverty (affluence)
across neighborhoods (defined by Massey and Denton as poverty concentration).See isolation
index above
Thresholds:
Poor: below federal poverty line
Affluent: $75,000 (top 12% of the 1989 family income distribution) |
(Waitzman and Smith, 1998) |
1 The dissimilarity
and the isolation index are not independent of the mean and variance of the income
distribution. For this reason, Jargowsky has proposed the use of NSI and NSI2
.
References
Jargowsky, P.A. (1997). Poverty and place: ghettos, barrios, and the American city.
Russell Sage Foundation, New York.
Massey, D.S. and N.A. Denton (1988). The dimensions of residential segregation. Social
Forces, 67:281-315.
Massey, D.S. and N. A. Denton (1993). American apartheid: Segregation and the
making of the underclass. Harvard University Press, Cambridge, Mass.
Waitzman, N.J. and K.R. Smith (1998). Separate but lethal: the effects of economic
segregation on mortality in metropolitan America. Milbank Quarterly, 76:341-73.
Addendum:
Dolores Acevedo-Garcia and Kimberly Lochner have written a chapter on residential
segregation and health to appear in Neighborhoods and Health (Ichiro Kawachi and
Lisa Berkman, Editors) to be published by Oxford University Press. The chapter provides a
review of the area for the reader who wishes more in depth coverage of the subject than is
provided in the Web site chapter. A pdf is available of the chapter and of
the chapter appendix (which contains the
information in this Web chapter); the authors request that no citations be made from
either pdf. |
