Introduction to the Use of Geographic Information

Systems in Public Health

Elio Spinello, MPHCalifornia State University, Northridge

Readings

Abstracts – 1st Annual International Health Geographics Conference – Infectious Diseases

Geographic Information Systems and Public Health: Mapping the Future Public Health Rep 1999; 114: 359-373 July / August, 1999

Learning Objectives Develop awareness of the basic

capabilities of Geographic Information Systems in Public Health

Understand basic concepts associated with GIS software

Understand specific ways in which GIS can be used in Public Health

Learning Objectives

Develop familiarity with terminology related to GIS

Understand issues related to privacy and confidentiality of records using in GIS software and maps which are produced by GIS software

Performance Objectives

Determine whether a particular study would benefit from GIS as a tool.

Determine the need for a data security method to be applied to a published map created with GIS software.

GIS TerminologyGeocoding

Append latitude and longitude to an address

CentroidCenter of a region

LayerOne type of geography on a map

GIS Terminology

FeaturesAnything on a map

AttributesCharacteristics of features

Thematic mappingVisualization of feature attributes

GIS Concepts

Types of geographyRegions (polygons)PointsLines

Example of a Theme Map

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I10 I10

I10

I10

I210

I405

I5

Los Angeles

MI's per Sq. Mile

.0 to 6.2

6.2 to 13.1

13.1 to 19.2

19.2 to 24.5

24.5 to 36.9

36.9 to 95.8

Hospital Beds

" 6

" 649

" 1,291

" 1,934

Layers ZIP Codes Interstates Counties

" Hospitals

San Fernando ValleyMyocardial Infarctions/Sq. Mi.

1/95 to 12/95

GIS Terminology

Projections.Compensate for curvature of the earth.

Types of Graphic Images

RasterMade up of pixelsNo relationship between elements

VectorPoints connected by lines

Data Requirements for Use of GIS Software

Data must be organized geographically

Records must include addresses or,

Records must include the region the point is located in (such as a zip code, census tract, etc.)

Types of Applications in Public Health

AnalyticalReportingData transformationSpatial Database Queries

Examples of Spatial Database Queries

Identifying and locating disease clusters

Locating target populationsIdentifying and locating

community resources useful for intervention programs

What Types of Studies Can Benefit From a GIS?

Calculation and visualization of morbidity and mortality rates for regions

Calculation of distance variables for statistical testing

Data visualization from a spatial perspectiveIdentifying geographic patterns

Risk communicationCommunicating geographically related risks

What Types of Studies Can Benefit From a GIS?

What Types of Studies Can Benefit From a GIS?

Disease cluster analysisLocating larger than expected incidences of a disease related by time and place

Analytical Barriers to Cluster Analysis

Imprecise measure of timeImprecise measure of place

Incomplete clinical data

Disease Cluster Analysis

For there to be causation, the risk must:Be in geographical proximity to the case, and…

Pre-date the disease

Privacy and Confidentiality Issues

Problem: maps may contain sufficient detail so that individual cases can be identified.

Primarily an issue when maps are released to the public or included in published work.

Methods to Protect Confidentiality

Introduction of ErrorPoints are randomly dispersed

Limitation of DetailDetailed layers, such as streets are not displayed with points.

Methods to Protect Confidentiality

Suppression of recordsRecords which meet very limited criteria and are few in numbers are not shown or disguised

Large Symbols

Example of Large Symbol Method

Methods to Protect Confidentiality

Convert points into attributes.Rather than display points, the points are aggregated to regions and the regions are themed by color based on the the number of points they contain.

Commonly Used GIS Programs

Atlas GIS (ESRI)ArcView GIS (ESRI)ArcInfo GIS (ESRI)MapInfo (MapInfo)