Relating residential segregation to communicable and non-communicable disease outcomes

EPID 684
Spatial Epidemiology
University of Michigan School of Public Health

Jon Zelner
[email protected]

Theme for this week

How do segregation measures map onto the mechanisms that drive health?


  • Coming to grips with the measurement of segregation and its impact on the spatial and social distribution of health outcomes

  • Segregation and COPD risk

  • Segregation and STI risk

Segregation and Gonhorrhea Risk in the U.S.

The many measures of segregation employed by Biello et al.

What is the isolation index?

Often defined as the proportion of contacts an individual in a minority group in a population has with members of that same group.

Sometimes paired with the interaction index

Interaction quantifies the proportion of minority group member’s contacts that occur with the majority group.

How do you measure isolation?

\[ Z = \sum_{i} \frac{a_{i}}{A} \frac{a_{i}}{n_i} \]


  • \(a_i\): Number of minority members in area \(i\)
  • \(b_i\): Number of majority group members in area \(i\)
  • \(A\) total number of minority group members
  • \(B\) total number of majority group members, where \(A < B\).
  • \(n_i\) number individuals in area \(i\), i.e. \(a_i + b_i\)

What is unevvenness or dissimilarity?

  • The proportion of members of a group that would have to move to a new location to end up with a random distribution of those individuals in space.
  • Goes from 0 to 1.

How is dissimilarity measured?

\[ D = \frac{1}{2} \sum_{i=1} \mid \frac{a_i}{A} - \frac{b_i}{B} \mid \]


  • \(a_i\): Number of minority members in area \(i\)
  • \(b_i\): Number of majority group members in area \(i\)
  • \(A\) total number of minority group members
  • \(B\) total number of majority group members, where \(A < B\).

What are some other dimensions of residential segregation?

Some canonical definitions from (1):

“Minority members may be distributed so that they are overrepresented in some areas and underrepresented in others, varying on the characteristic of evenness.”
“[Minority group members] may be distributed so that their exposure to majority members is limited by virtue of rarely sharing a neighborhood with them.”
“They may be spatially concentrated within a very small area, occupying less physical space than majority members.”

“They may be spatially centralized, congregating around the urban core, and occupying a more central location than the majority.”


“[A]reas of minority settlement may be tightly clustered to form one large contiguous enclave, or be scattered widely around the urban area.”

Grappling with the complexity of social-spatial relationships

  • The spatial expression of social inequality is complex.

  • Our measures are necessarily reductive, and that’s OK…

  • IF and only IF (⟺) we use these measures carefully without losing sight of the mechanisms and outcomes we care about.

  • In pairs: In this google doc, brainstorm 🧠 ⛈️ some ideas about what dimensions of inequity these different measures capture.


Comparing Segregation and Clustering Metrics

What time is it? It’s hands-on time!

Thoughts on the readings?

  • Take 2m on your own to take a look back at the readings.

  • What struck you as interesting/confusing/frustrating?

  • What gaps do you see in the relationship between the segregation measures and disease outcomes assessed?

What might not sit right about this statement?

“Isolation may increase the risk for gonorrhea through its effect on social factors as well. Social norms — which also can be transmitted — have been shown to be associated with sexual risk among adolescents and among Black women. In isolated communities, within group norms for risky sexual behavior might be strengthened.” (2)

What are the characteristics of COPD?

  • Chronic inflammation of airways and alveoli.
  • Characterized by chronic cough and sputum production.
  • Severity of cough and sputum associated with worse COPD outcomes.
  • Increased risk of respiratory infection.

How does segregation impact COPD disparities?

Relationships between segregation and COPD from (3)

Why is mediation analysis useful for understanding impact of segregation on health?

Segregation is a construct reflecting a complex mix of social and environmental factors.

What does a mediation model measure?

  • Total effect: Relationship between distal factor and outcome including direct and indirect effects.

  • Direct effect: Relationship between distal factor and outcome adjusted for mediator.

  • Indirect effect: Impact of distal factor via a more proximal one.

  • In an additive model: indirect = total - direct

Next Time


Massey DS, Denton NA. The Dimensions of Residential Segregation. Social Forces [electronic article]. 1988;67(2):281–315. ( (Accessed January 22, 2020)
Biello KB, Kershaw T, Nelson R, et al. Racial Residential Segregation and Rates of Gonorrhea in the United States, 2003. American Journal of Public Health [electronic article]. 2012;102(7):1370–1377. ( (Accessed December 15, 2019)
Woo H, Brigham EP, Allbright K, et al. Racial Segregation and Respiratory Outcomes among Urban Black Residents with and at Risk of Chronic Obstructive Pulmonary Disease. American Journal of Respiratory and Critical Care Medicine [electronic article]. 2021;204(5):536–545. ( (Accessed February 9, 2022)