GIS needs to be used appropriately: this is a field where expert help is necessary, and responsible consultants should always make very clear what a GI project can do within a specific project, and what it cannot.

GIS tools are particularly useful for:

• analysing large quantities of data, such as statistics for individuals or buildings, across a geographic area
• analysing several different kinds of data across an area and understanding how they relate to one another e.g. property types, employment patterns and property values for a given neighbourhood
• analysing changes to data over time and visualising the results to allow their ready comparison; projections of future scenarios can be incorporated in the same way, although using any model to predict the future is high-risk
• visualising the results of analysis, to allow even non-expert users to understand them easily
• seeing in these visualised results patterns, trends, peaks and troughs which would not otherwise have been visible
• making it easier to spot errors and anomalies, smoothing out the effects of micro-scale phenomena and creating the most accurate possible picture of what’s at work
• adding value to data as an asset.

The use of GI tools can create its own issues, however:

• its technical nature can make results appear more reliable than they are; poor operators can hide assumptions and errors in a composite results, while users can be ‘blinded with science’ and not apply their usual standards of questioning to what they are being told
• the results of a GI analysis can only ever be as accurate as the data which underlies them, and should only ever be reported at the finest spatial scale of any dataset used – if one input is data collected at county level, for example, the results of the analysis cannot safely be used to make decisions at district or ward level
• the availability of data at the required scale at a reasonable cost is a universal issue.