Intro to GIS for Public Health

Author

Dr Deepak Varughese

Epidemiology

The study of the distribution of Disease and Disease Related States

  • By Person

  • By Place

  • By Time

By Person

Who is likely to get the disease? What are the risk factors

  • Case Control Studies

  • Cohort Studies

  • Randomized Control Trials

  • Quasi-Experimental Designs

By Time

How is the disease changing over time?

  • Time Series Analysis

  • Cohort Studies

  • Repeated Cross Sectional Studies

By Place

  • Ecological Studies

  • Case Control Studies

  • Difference in Difference Designs

Who? Where? When?

GIS Provides the “where” in the traditional “who, where, when triad” in epidemiology

It can also be clubbed with the when - to provide “Spatio-Temporal” Insights.

GIS

  • Geographical Information Systems

  • Geospatial Information Systems

  • Spatial Data Science

Is Mapping in Public Health New?

Advantages of Hand- Drawn Paper Maps?

  • Local Knowledge?

  • “The Map is not the territory” - In-Depth knowledge of intricacies that may not be captured on the map.

  • Accessibility - Do not need special training or tools

  • “Fail Safe” - Do not depend on technology / power requirements etc

Disadvantages of Hand Drawn Paper Maps

  • Not to scale?

  • Precision in distance , etc

  • Difficult to stack maps on top of each other

  • Static and Difficult to Update

  • Limited by size and scale

So what then is GIS anyway? Is it just a digital map?

A GIS system has 2 main components

  • A geography or shape (eg - Points, Polygons, Boundaries, Rasters) - WHERE

  • A table storing information - WHAT

GIS vs Static Maps

Creating Maps is one of the many possibilities of GIS

GIS is not about simply displaying static information but allowing the users to ask questions of the data

  • What is the shortest distance from Point A to Point B

  • What is an ideal catchment area for my services

  • How is the distribution of air-pollution related to the distribution of COPD

Tools used for GIS

A wide combination of software solutions can be used for GIS related work.

  • ArcGIS - Commercial , Proprietary - Licences are approximately (Prices could vary from USD100 to USD3800 per Year depending on licence types)

  • QGIS - Free and Open Source.

Other Useful Programming Languages handy for GIS

  • Python

  • R

  • SQL / PostGIS

Types of Data in GIS

  • Vector Data

    • Points

    • Lines

    • Polygons

  • Raster Data

    • A type of Digital photograph that represents Continuous Data where values change gradually over space

      • Population

      • Elevation

      • Land Use / Land Cover

      • Temperature

Real World to GIS Layers