On the Quality of Countour Maps

 by Thomas Polfeldt

 Research Report 1998:7

 Department of Statistics, Stockholm University, S-106 91 Stockholm, Sweden

 Paper presented at the 9th International Conference on Quantative Methods for the Environmental Sciences,
Gold Coast, Qld., Australia, July 3-6 1998.


Contour map, also called isopleth maps, are used fairly often in environmental statistics. Examples are maps showing the levels of pollutants or depositions over a certain area. Kriging and other estimation techniques can be used to produce the data for such maps, and prediction (and other) errors can then be associated with each point. It is shown in a simple case that the values selected for the contour levels should differ from each other by several multiples of the prediction error (or some average prediction error). If not, the probabilities for the values shown on the map to be error will be too high. Limitations and extensions of the ideas are briefly discussed.

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Last update: 1998-10-01 / KH/MC