1. Geographic Information Systems
Natalie Stewart
Public Health Information Analyst
I’m here to talk to you today about MapInfo, I’m part of the Corporate GIS Meetings that is currently undergoing reconfiguration. We meet on a monthly basis to talk about MapInfo as well as other GIS systems such as ARCGIS and Local View. My expertise is in MapInfo within a Public Health Context but what I’m going to present today is universal and can be applied across directorates and service functions.

2. Contents What is MapInfo? Historical Context Geocoding Thematic
Grid Mapping
How can the use of GIS inform policy & practice?
Limitations
Childhood Obesity
Questions?
Birmingham Public Health Information & Intelligence Team

3. What is MapInfo?
*MapInfo Professional is a desktop geographic information system (GIS) software product and is used for mapping and location analytics. MapInfo allows users to visualise, analyse, edit, interpret, understand and output data to reveal relationships, patterns, and trends. MapInfo allows users to explore spatial data within a dataset, symbolize features, and create maps. *
This description has been pulled directly from the MapInfo Professional user page, it’s quite an accurate description to users who are familiar with mapinfo and creating maps and datasets but to those of you who are new to it, it might not mean an awful lot. I will come on to worked examples very soon but first I’d like to give a very brief historical overview of mapping and what it has to offer.
Birmingham Public Health Information & Intelligence Team

4. Dr John Snow’s Cholera Map
How often does a map change the world? Well, in 1854, one produced by Doctor John Snow, altered it forever.
In the world of the 1850s, cholera was believed to be spread by miasma in the air, germs were not yet understood and the sudden and serious outbreak of cholera in London's Soho was a mystery.
So Snow did something information analysts often do now: he mapped the cases. The map essentially represented each death as a point (the larger the point the more deaths at that location), it became apparent that the cases were clustered around the pump at the intersection of Broad Street and Little Windmill Street.
At a local brewery, the workers were allowed all the beer they could drink - it was believed they didn't drink water at all. But it had its own water supply too and there were consequently fewer cases.
In nearby Poland street, a workhouse was surrounded by cases but appeared unaffected: this was because, again, it had its own water supply.
It turned out that the water for the pump was polluted by sewage from a nearby cesspit where a baby's nappy contaminated with cholera had been dumped. But he didn't just produce a map; it was one part of a detailed statistical analysis. Snow's study was a major event in the history of public health and health geography, and can be regarded as the founding event of the science of epidemiology.
Birmingham Public Health Information & Intelligence Team

5. Geocoded Maps Map showing the location of all schools in Birmingham.
For this type of map we need a full postcode which is then converted to an 8 character postcopde so MapInfo can read in the data, we then match the postcode to its corresponding easting & northing. The terms easting and northing are geographic Cartesian coordinates for a point. Easting refers to the eastward-measured distance (or the x-coordinate), while northing refers to the northward-measured distance (or the y-coordinate). This helps us display points on the map, usually locations of services such as schools (as pictured), GP’s, Dentists etc. Helpful to determine where service provision is needed, location can influence health.
Birmingham Public Health Information & Intelligence Team

6. Thematic Maps
Map showing deprivation levels in Birmingham on an LSOA basis.
There are 40 electoral wards in Birmingham with an average population size of 27,300 based on the 2013 mid-year pop estimates. There are 641 LSOA’s in Birmingham, an LSOA is a Lower Layer Super Output Area and are made up of roughly 1,500 residents and 650 households. SOAs give an improved basis for comparison because the units are more similar in size of population than, for example, electoral wards; we’re able to show variation in a much clearer way, if deprivation was mapped at a ward level it would mask the smaller areas with very high deprivation. They are also intended to be stable, enabling the improved comparison and monitoring of policy over time. In addition, figures for user defined geographies are aggregated and best fitted from data held for OAs and SOAs.
Birmingham Public Health Information & Intelligence Team

7. Grid Maps
Map shows counts of road traffic accidents by location in children aged 0-15 over a 4 year period ( ).
Grid mapping used to show hotspots, at a much lower geographical level – thematic data showed at a postcode level. The Grid default template assigns blue to the minimum value and red to the maximum value. These minimum and maximum values are also expressed as percentages of the range. These color settings/values are known as inflection points and will display in the legend with a particular color, value and percentage. If a cell has the exact value as the inflection point, it will display that color on the map. A cell value that falls between two inflection points displays with the color that is in between the colors of those inflection points. MapInfo provides two types of interpolators for creating grid themes. These are Inverse Distance Weighting (IDW) and Triangulated Irregular Network(TIN). he IDW interpolator is best suited for data values that produce arbitrary values over the grid, that is, data that does not have any relationship or influence over neighboring data values, such as population. This method of interpolation also works well for sparse data. The IDW interpolator calculates the value of grid cells that cover the mapping area. Each data point value from the source table that is considered in the calculation for a cell value is weighted by its distance from the center of the cell. Because the interpolation is an inverse distance weighting calculation, the farther the point is from the cell, the less influence its value will have on the resulting cell value.
Birmingham Public Health Information & Intelligence Team

8. How can the use of GIS inform policy & practice?
Research Tools and Planning
Constructing mathematical models
Service planning and optimisation
Making predictions
Spatial Decision Support Systems
Infrastructure – roads, towns, services
Census – population statistics
Medical resource (hospitals, clinics, available beds)
Emergency Response Systems
disease registers systems
Birmingham Public Health Information & Intelligence Team

9. Limitations of mapping
Stacking
Requires full postcodes
Expensive software
Licenses
Training
Procuring geographic layers
PSMA
Caveats need to be considered when interpreting maps with geocoded points due to stacking which will results in one point being shown whilst others are hidden such as locations that have the same postcode or a locations that are in very close proximity.
MI only works with full postcodes i.e. B7 4BG, not B7.
MI is an expensive between £1,764 for standard and £2,118 for premium – license costs to consider!
Training – needed to use MapInfo, it’s not intuitive, training is an additional cost.
Used to have to pay for layers such as Birmingham/ Wards/ LSOA’s etc, now we can download them from Public Sector Mapping Agreement but we have to draw our own boundaries so technical knowledge of how to redistrict is a must.
Birmingham Public Health Information & Intelligence Team

10. Childhood Obesity
This map will help influence commissioning decisions and will inform planning and has been a multi-directorate piece of work. Buffers are very useful for selecting all the features in one layer that are within a certain distance of another feature. In this map we have an 800m buffer around selected schools showing the distance between schools and hot food takeaways. Selected schools are ones that fall into the categories of having high and statistically high prevalence of overweight and obese year 6 pupils as well as schools that have low and statistically low prevalence of overweight and obese year 6 pupils. Additional analysis in SQL has shown that there are 4 schools in the high category that have 10 or more hot food takeaways within 800m. 31 schools in total ranked as high with a total of 90 hot food takeaways within 800m. The thematic layer is the prevalence of year 6 overweight and obese children, the darker the blue the higher the prevalence. The majority of the high, and significantly high schools fall into wards which have higher prevalence of overweight and obese children.
Birmingham Public Health Information & Intelligence Team

11. Questions/ comments?
Contact details: - Natalie Stewart Public Health
Birmingham Public Health Information & Intelligence Team