Monday, November 12, 2007

Road to nowhere

First published online 15th December 2006

I have been reading with interest the common reports of problems that motorists have been having with satellite navigation systems.

Having been able to inspect the data which these systems use, it comes as no surprise to me that there have been problems. Even had I not seen the data, we all know that even the smallest databases contain errors - databases of the size and complexity of those used in GIS systems, which attempt to represent an ever changing world, will inevitably contain many inaccuracies.

Many of the problems reported seem to revolve around motorists adopting a blind trust in their satellite navigation systems - something that almost everybody using data, including those doing it professionally, also tend to do. Show a person a piece of data, such as the string "London", and that person will make immediate assumptions about that data. However, one of my rules for good data management is to take data in context - that string may be a city in one context, but may refer to a name in another, for example.

Furthermore, the databases used by these satellite navigations systems do not contain data required for some drivers for choosing routes - height and width restrictions on roads, for example.

If users of satellite navigation systems were to take the data they are given in context - i.e. using that data along with information provided by road signs, maps and the evidence of their eyes, we would find fewer of them wedged in bends, unable to get up steep hills, and having to cross fields to get to roads they thought they were on already.

Other data users and managers would be well advised to consider if this metaphor applies to them ...

(c) 2006 Graham Rhind. Reproduction only allowed with permission. Comment and dialogue welcome.

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