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Section 22. Using Small Area Analysis to Uncover Disparities

Learn how to use small area analysis to evaluate the social and economic disparities in your community.


  • What do we mean by small area analysis?

  • Why conduct small area analysis?

  • When should you conduct small area analysis?

  • Who should be involved in conducting small area analysis?

  • How do you conduct small area analysis?

Community assessments of various kinds often require us to use statistics and other information relating to a certain area. Usually, that area is a city, a county, or even a state or province. That kind of information doesn’t always tell us what we need to know, however.

Suppose, for instance, you’re examining health disparities in a large city. You might have citywide statistics telling you about such things as the frequency of various diseases and medical conditions, emergency room visits, and health costs per resident. What these statistics won’t tell you is the differences among neighborhoods or groups within the city’s population.

What population(s) bear a disproportionate burden of health problems? Is there a neighborhood where disparities are particularly prevalent? Without answers to these kinds of questions, you can’t focus prevention and care where they’re needed or identify environmental factors that may lead to disparities in health among different groups within the population of the city as a whole. The same is true for issues other than health as well – violence, access to goods and services, traffic flow, and numerous others. If you don’t have information pinpointing where problems – and assets – exist, you can’t address or use them properly.

This section deals with just that issue. By using small area analysis, you can understand where the real needs are, tailor problem solutions to the areas where they’re really needed, and divide resources so that they will be as effective as possible. We’ll examine what small area analysis is, when it’s appropriate, and how to conduct it.

What do we mean by small area analysis?

The definition of a small area depends on your needs. It may be a geographic area, a political or administrative district, or even a particular group of people.

The point of small area analysis is to focus on specific areas or populations so that you can see differences among small areas within a larger statistical pattern. If, for instance, the smallest unit for which statistics exist is a county, there may be great differences among different towns or areas within that county when it comes to a particular issue, say the percentage of children with asthma. The statistics for the county as a whole may be average, but one or two small towns may account for the majority of the cases, with the rest of the county experiencing almost no childhood asthma. Clearly, the focus ought to be on those towns where asthma is the most serious.

The difficulties in conducting small area analysis come in defining the areas you’re concerned with and in finding ways to obtain information for those areas. We’ll discuss both these issues – defining small areas and gathering information – in more detail in the how-to part of this section.

As with most efforts described in the Community Tool Box, small area analysis can often work best when it’s possible to involve the community in planning the assessment. Those who live in the community and are affected by the issues that the assessment reveals may have good ideas about how to divide the larger community into small areas (i.e., towns, neighborhoods, housing developments, etc.), and about what to look for.

Why conduct small area analysis?

  • Small area analysis can identify disparities in health and services. This can uncover lack of access, underserved areas, and populations that suffer more than others from various negative health, economic, and social conditions.
  • It can uncover issues you wouldn’t otherwise see. A city or province may look problem-free, but small area analysis can identify geographic or population pockets within the larger area where problems are serious.
  • It helps with deciding where to allocate resources. If you know where problems are most serious, you can target scarce resources appropriately.
  • Small area analysis clarifies what problems, issues, and assets exist where.
  • Small area analysis can help identify causes or contributing factors to a condition. By comparing the statistics and situations of a number of areas, you may be able to see why a condition exists in one area and not in another. A nearby industrial facility may be the difference between an area of high childhood asthma rates and one where the rates are low, for example.

The classic example of this is from 19th Century London. The physician John Snow, by mapping individual cases, traced the spread of a cholera epidemic to a particular public water pump. When the pump was shut down, the epidemic subsided.

When should you conduct small area analysis?

  • When small areas are what you’re responsible for. If you’re part of a coalition representing a number of neighborhoods or several small rural towns, for instance, or if you’re part of or working with a public health agency, you’ll have to consider the needs of several small areas within a larger region.
  • When you have to allocate limited resources. Small area analysis can inform your decisions about where and how to use your funding, personnel, and other resources most effectively and most efficiently.
  • When overall statistics don’t seem to be telling the story. You’re aware of a large and apparently growing number of diabetes cases in an inner-city clinic, but the statistics for the city as a whole don’t seem to reflect this. Small area analysis can help you understand the reality.
  • When you’re trying to pinpoint sources or causes of conditions. Where do most instances of youth violence take place, for example? Particular blocks or housing projects?

Who should conduct small area analysis?

  • Citizens concerned with or affected by conditions that create disparities among groups in different areas or with different characteristics.
  • Public health agencies, officials, and coalitions
  • Other public agencies that provide services (e.g., welfare, children’s services)
  • NGOs (non-governmental organizations) and community-based human service organizations
  • Community activists
  • Police and fire departments, and municipal service departments
  • Hospitals
  • Community developers
  • Community and regional planners

How do you conduct small area analysis?

Assessing and analyzing the needs and assets of small areas is no different from doing the same for larger areas, with one exception: data about small areas may be much harder to come by. The availability of information depends on a number of factors: who is gathering it (the state, federal government, county, etc.), what it’s meant to be used for, and how well-defined the areas are for which it’s collected. Choosing small areas for analysis may be a matter not only of what you want to learn, but also of which areas you can gather data for, where you’ll get it, and what you’ll do with it.

1. Ensure community participation. Involve community members at the very beginning of the process. They can help with all the steps that lead to a comprehensive assessment, they’re likely to know the small areas well, they are the ones likely to be most affected by your effort, and their involvement can provide information you otherwise might not have access to.

Enlist those you know to help you find the people and groups that should be involved. If you don’t have direct contact with key informants, leaders, or others with deep connections in the community, you might start with community meetings, notices sent home with children from school, and other public information strategies to assemble a core group. That group can then help to identify and recruit others whose participation is important to your effort.

2. Identify the outcomes you hope will result from small area analysis. What exactly are you trying to accomplish?

  • Find and eliminate disparities among areas or populations.
  • Address issues in places or among populations where they are most serious.
  • Identify the potential environmental or social factors that may be responsible for the disparities or conditions you’re concerned with, and plan how your effort will address them.
  • Figure out how to most effectively allocate resources in order to have the greatest impact.

3. Define the small areas you’ll examine. In some cases, your choices might be obvious. If you’re responsible for a county, for instance, you might want to divide up the area by town.

In other cases, defining small areas may not be so simple. The real question is often whether it’s possible to get information on the areas you’re interested in. Government departments and agencies, municipalities, businesses, and non-profit organizations all may collect information in different ways and for different geographic and demographic units. Some data may be available for zip codes or other postal districts; some may refer to particular populations; some may only describe large areas, such as counties or provinces. A few examples of small areas you might want to examine:

  • City or town
  • Neighborhood
  • Rural village or group of villages
  • City block
  • Public housing complex or other specific housing development
  • Favela or similar unincorporated living area
  • Specific racial, ethnic, cultural, or faith group
  • People with a particular health condition
  • Public health or other government agency service area
  • Service area of a hospital, human service organization, etc.
  • County
  • Water district
  • Census tract

Defining small areas, therefore, may be a matter of balancing the availability of useful data with your areas of concern.

4. Choose the information you’ll look for. What you’re seeking should tell you something about the issues you’re concerned with, and help you understand and address disparities among areas and population groups. There are several possibilities here, any or all of which may be important to your work.

  • Demographics. This category includes:
    • Population size
    • Age
    • Income
    • Education
    • Race/ethnicity
    • Country of birth/citizenship
    • Employment
    • Marital status
    • Family size
    • Home ownership
  • Environmental conditions that affect issues of concern. Some examples:
    • Land use policies
    • Location of industrial plants
    • Density of fast food and alcohol retailers
    • Access to services by location or public transportation
    • Access to safe areas to walk, jog, bicycle, etc.
  • Social determinants related to disparities. These can include:
    • Income inequality
    • Racial or ethnic prejudice
    • Access to health care and health insurance
    • Behavioral norms held by social groups, cultures, religions, etc.
    • Social capital. This is the web of social connections, trust, credits, and obligations that people accumulate in their everyday contact with others. The less social capital people have, the more at risk they may be for health and other problems.     
    • Food insecurity
  • Context. This refers to the setting in which the small area and its residents live and function.
    • Area history. Are there groups with a history of working together on common issues or goals?
    • Relationships among groups and key individuals.
    • Is there new or expanded leadership, or a loss of/change in leadership?
    • Is there political commitment to change conditions?

5. Identify potential data sources for the small area(s) you’re concerned with. Some possibilities:

  • The census in the U.S. and other countries, in addition to counting people, gathers basic information on everyone and detailed information on a smaller number of individuals and families. Data on education, income, living conditions, employment, and numerous other categories are often available. You can search the census in a number of ways:
    • By state or province, county, sub-county, city or town, parish, etc. Some census data are broken out by administrative districts, such as states or counties, and/or by community.
    • Census tract. In the U.S. Census, all areas of the country are divided into census tracts. To the extent possible, all the households in a tract are similar in terms of demographics, economic status, and living conditions. A census tract has between 1,500 and 8,000 people, with the average at about 4,000.
    •  Census block. Census tracts are further broken down into blocks, smaller population units that may cover large geographic areas with few or no people, or – in metropolitan areas – may contain a single apartment house that is home to several hundred people.
  • Survey records.
    • BRFSS (Behavior Risk Factor Surveillance System)—State/County-level data, with rare oversampling to represent adults in particular smaller areas
    • YRBS (Youth Risk Behavior Survey) data representing school-aged youth in the school district, with potential sub-analyses by high school catchment area
  • Organizational and institutional files often contain valuable information about health, living conditions, income, etc. for very specific small areas and populations. Some organizations and institutions that might be helpful include:
    • Hospitals
    • Health and mental health clinics
    • Human service organizations
    • Schools and colleges
    • Economic development organizations

Most of these protect the privacy of individuals, but may have figures for the areas or populations they serve.

  • Municipal records – the records kept by cities and towns and their departments and boards – can often be helpful. Among these might be:
    • Police records
    • Planning department files (city/town/county)
    • GIS and other maps
    • Vital statistics (births, marriages, deaths)
    • Municipal boards (Board of Health, Zoning Board, etc.)
  • State and federal government agency files may be public records or may be available – again, with individual identities protected – for research purposes. Some that could prove useful:
    • CMS databases
    • Department of Education
    • PRAMS (CDC Pregnancy Risk Assessment Monitoring System)
  • Direct, hands-on information gathering can be effective when the areas you’re concerned with are small enough and you have the people – often volunteers – willing to go out and get the data. Some methods of direct data gathering:
    • Surveys, oral or written.
    • Individual and group interviews
    • Observation – watching or participating in the activities of people, places, conditions, etc. where they exist.

Be aware that if you decide to gather your own data, volunteers or staff members will probably need some training, especially if they have no real experience of asking people for information or of research. How to find survey and interview subjects, how and when to make observations, effective recording techniques, the use of any special equipment – all of these and more may be part of a training for data collectors.

6. Determine how you’ll analyze the information once you have it. This is where “analysis” comes in. How will you extract what you need from the data you have? That depends on at least three factors:

  • The quality of the information. Where did it come from, how was it gathered, and how accurate is it?
  • The timeliness of the information. As we’ve mentioned, data that is a year or more out of date may not reflect current reality. The problem is that sometimes nothing more current is available. If there are sets of data from each of several recent years, even if they’re somewhat out of date, they may indicate trends that you can use in your assessment. If there is only one set of out-of-date data, however, it doesn’t necessarily give you useful information about what is happening now.

If there is no up-to-date information, you have some choices as to how to proceed:

  • You can simply use the data you have, and assume that it is still reasonably accurate. In many instances, this will work fine.
  • You can look for trends in the data (see below), and estimate what the current numbers should be, based on past increases or decreases.
  • You can compare small areas with the larger area, and estimate disparities similar to those in the existing data.

None of these is a perfect solution, but they at least give you something reasonable to base your planning on.

  • The geographic and demographic areas the information describes. The ideal, of course, is finding information that relates specifically to the areas you’re concerned with – urban neighborhoods, rural farming villages, townships, housing projects, pockets of particular populations. You may be able to get this information using other geographic or demographic units – postal districts, for instance. On the other hand, you may not be able to get information specific to the areas you want, and have to settle for information relating to somewhat larger or geographically different areas.

Using childhood asthma as an example, we’ll list some questions to consider as you analyze the data:

  • Do one or more neighborhoods within a city have a higher rate of asthma among children than the city as a whole?
  • What are the differences in the rates of childhood asthma between the neighborhoods?
  • Do children of different racial or ethnic groups in a particular neighborhood or housing project seem to have different rates of asthma?
  • Are there factors in the physical environment that might contribute to or explain differences? In the case of our example, these might include industrial facilities, nearby busy roads, rodents, indoor chemicals, or dumps that could be responsible for pollution or particles in the air that might contribute to asthma. Volatile organic compounds, or VOCs, for instance, are found in many paints, solvents, glues, and other substances used in indoor and outdoor construction processes or materials. Many people, particularly those with asthma or other similar conditions, find that VOCs affect their breathing.
  • Are there social, political, and/or economic factors (social determinants of health or SDOH) that might contribute to or explain differences? Poverty, for instance, or racial or ethnic discrimination might force people to live in polluted areas or substandard housing.
  • Are there cultural differences among the residents that account for different social norms for health behaviors?
  • Are there trends that show the issue increasing or decreasing in particular small areas or among particular population groups?
  • Are numbers dependent on when measurements were taken?
  • Do you know something the numbers don’t? The recent start of a new initiative or program, a recent shift in population, new or lost leadership, new funding – any of these and numerous other factors can have a positive or negative impact on the conditions you’re examining. If you’re aware of events or conditions that have arisen since your information was collected, you should take them into account.

7. Evaluate your small area analysis effort. Small area analysis is often ongoing. Even if your effort is not, the chances are that you’ll want to do a small area analysis again. It’s important to know what worked well, what kind of information was most valuable, whether your understanding of causes and identification of trends were accurate, and whether the information you gathered was in fact instrumental in your being able to address the issues and disparities you were concerned with.

If you collect and analyze the data carefully, small area analysis can help you to a better assessment of the larger community, and allow you to direct your effort where it will do the most good.

In Summary

Small area analysis is the practice of separating out the data for small geographic areas and/or populations – neighborhoods, rural villages, housing projects, etc. – in order to identify and understand disparities among them and between them and the larger statistical area. This makes it possible to concentrate efforts and resources where they are most needed and where they will bring the greatest return.

Conducting small area analysis is a process that includes:

  • Encouraging community participation
  • Identifying the outcomes you hope to gain from conducting small area analysis
  • Defining the small areas you’ll examine
  • Choosing the information you’ll look for
  • Determining where to find the information
  • Deciding how to analyze the information once you have it
  • Evaluating your small area analysis effort

Small area analysis can be tremendously helpful in understanding the real needs and assets of your community, and in directing efforts and resources accordingly.

We encourage the reproduction of this material, but ask that you credit the Community Tool Box:

Stephen Fawcett
Christina Holt
Jerry Schultz
Phil Rabinowitz

Online Resources

Alameda County Health Status Report, Chapter 1: Demographic and Social Profile, and Chapter 2: Health Inequities. Alameda County Health Department. (2006).

Analysis of health and disease in small areas. Health Knowledge, UK.

Are We Closing the Disparities Gap? Small-Area Analysis of Asthma in Chicago. Edward T. Naureckas, MD; and Sandra Thomas, MD, MSc, American College of Chest Physicians (Chest Journal), 2007.

Assessing Community Health Status: Establishing Geographic Areas for Small Area Analysis in UtahUtah's Health: An Annual Review, Vol V., 1997-1998. Salt Lake City, UT: University of Utah, The Governor Scott M. Matheson Center for

Diversity and Disparity: GIS and Small-Area Analysis in Six Chicago NeighborhoodsSteven Whitman,1,2,3 Abigail Silva,1 Ami Shah,1 and David Ansell1,2. Journal of Medical Systems, Vol. 28, No. 4, August 2004.Health Care Studies. Utah Department of Health: Haggard, L., Shah, G., and Rolfs, R. T. (1998.)

Google Dataset Search is a search engine tool that is useful in discovery of datasets.

Healthcare Hotspotting's toolkit and video offer a data-driven process for the timely identification of extreme patterns in a defined region of the healthcare system.

Health Inequities in the Bay Area from Bay Area Regional Health Inequities Initiative. (2008).

The Hot Spotters: Can we lower medical costs by giving the neediest patients better care? from The New Yorker. Gawande, Atul. (2011).

Hotspotting: The Driver Behind the Camden Coalition's Innovations from the Camden Coalition of Healthcare Providers (CCHP) works to improve the health of Camden, New Jersey residents through innovative approaches to increase quality, capacity, and accessibility within the city’s health care system.

Monitoring Small Area Growth with GIS: An Application to the City of Los AngelesSimon Choi, Ping Wang, Elizabeth Delgado, Sung Ho Ryu from the Southern California Association of Governments; and Kyuyoung Cho, Department of Urban Information Engineering, Anyang University, South Korea.

Small-Area Analysis, pages 898-901, in Paul Demeny and Geoffrey McNicoll (eds.), Encyclopedia of Population. Farmington Hills, MI: Macmillan Reference, 2003.

Small-Area Analysis: Targeting High-Risk Areas For Adolescent Pregnancy Prevention Programs. Jeffrey B. Gould, Beate Herrchen, Tanya Pham, Stephan Bera, and Claire Brindis. Family Planning Perspectives, vol. 30, No. 4, July/August, 1998.

Print Resources

Association for Community Health Improvement. Step 2: Determine the Purpose and Scope of the Community Health Needs Assessment. Community Health Assessment Toolkit.

Catholic Health Association. (March 2011 Draft). CHNA Step 2: Determine the Purpose and Scope of the Community Health Needs Assessment. Assessing and Addressing Community Health Needs.

Fawcett, S., Holt, C., & Schultz, J., (2011)  Report to the U.S. Centers for Disease Control and Prevention: Some Recommended Practice Areas for Enhancing Community Health Improvement.

National Association of County and City Health Officials. (2001.) MAPP Framework—All Phases: Phase 1: Organize for Success / Partnership Development; Phase 2: Visioning; Phase 3: Four MAPP Assessments; Phase 4: Identifying Strategic Issues; Phase 5: Formulating Goals and Strategies; Phase 6: Action Cycle. Mobilizing for Action through Planning and Partnerships: Web-based Framework Tool. Washington, DC: National Association of County and City Health Officials.

National Association of County & City Health Officials. (2008). Task 4: Define the Goals of the Assessment. Protocol for Assessing Community Excellence in Environmental Health.

Substance Abuse & Mental Health Services Administration. Step 1: Identify the Goals of the Needs Assessment. Community Needs Assessment Guide. U.S. Department of Health and Human Services.