Space - a neglected frontier? Adding the geographical component to research in the digital age
Ian Gregory, University of Portsmouth
There are three main components of data: attribute (theme), which tells us what the data are (statistical, textual, image etc.); temporal, which tells us when the data existed/are relevant for; and spatial, which tells us where the data refer to, whether a precise grid reference or something vaguer. It is with this spatial component of data, difficult to handle (whether on paper or in a database) and consequently neglected, that I am particularly concerned here.
GIS: A spatially-referenced database
Advantages of GIS
1. Structures a database
The International Dunhuang Project (IDP) is a good example (http://idp.bl.uk/). The project has a database of 40,000 paper manuscripts, printed documents and document fragments from a library in northwest China, dating from the fifth to the eleventh centuries. The library was excavated and the contents dispersed to Britain, France, China, Japan and Russia - and this is where the spatial element comes into play. The IDP project is an integrated digital library of these artefacts.
2. Data integration
History of the book:
Source: MacDonald B and Black F (2000) "Using GIS for spatial and temporal analyses in print culture studies", Social Science History, 24, pp. 505-36.
3. Data visualization
Choropleths:
Cartograms:
Virtual landscapes and fly-throughs can also be a valuable tool (e.g., those on the BBC web site at http://www.bbc.co.uk/history/interactive/virtual_tours/)
4. Spatial analysis
Net migration from the 'basic demographic equation'
NMt,t+n = pt+n - pt - (Bt,t+n + Dt,t + n)
Age and sex specific population, fertility and mortality data have been published decennially in Britain since the eighteen-fifties. However, as net migration is the residual it is highly susceptible to error; in particular, the impact of any boundary changes will appear as migration. By standardizing both population and mortality data from many dates onto a single set of target units we are able to calculate net migration rates for males and females in ten-year cohorts from ages five to fourteen to ages fifty-five to sixty-four (at start of decade).
Net migration for women aged five to fourteen at the start of the decade can be calculated as:
- Females aged fifteen to twenty-four at end of decade
- minus females aged five to fourteen at start of decade
- minus number of deaths in the cohort through the decade
Standardised time-series
Net migration rates among the 5 - 14 cohort:
Detailed attribute comparisons
Net migration rates among different cohorts in the 1920s:
Conclusions
- GIS allows improved handling of spatially-referenced data.
- Improved understanding of space allows:
- Structuring
- Integration
- Visualization
- Analysis
- It does not solve all the problems - in fact it creates many new ones:
With experience, GIS becomes simply an extension of one's analytical thinking...The system has no inherent answers, only those of the analyst. It is a tool for thought (J. R. Eastman, IDRISI Users' Guide (1992), p. 32).
