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Revisiting Kappa to account for change in the accuracy assessment of land-use models (2011)

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Title Revisiting Kappa to account for change in the accuracy assessment of land-use models
Published in Ecological Modelling, Vol. 222, No. 8, p.1367-1375. ISSN 0304-3800.
Author Vliet, van J.; Bregt, A.K.; Hagen-Zanker, A.
Date 2011
Reference(s) Centrum Geo-informatie, Laboratorium voor Geo-informatiekunde en remote sensing
Language English
Type Article
Abstract Land-use change models are typically calibrated to reproduce known historic changes. Calibration results can then be assessed by comparing two datasets: the simulated land-use map and the actual land-use map at the same time. A common method for this is the Kappa statistic, which expresses the agreement between two categorical datasets corrected for the expected agreement. This expected agreement is based on a stochastic model of random allocation given the distribution of class sizes. However, when a model starts from an initial land-use map and makes changes to it, that stochastic model does not pose a meaningful reference level. This paper introduces KSimulation, a statistic that is identical in form to the Kappa statistic but instead applies a more appropriate stochastic model of random allocation of class transitions relative to the initial map. The new method is illustrated on a simple example and then the results of the Kappa statistic and KSimulation are compared using the results of a land-use model. It is found that only KSimulation truly tests models in their capacity to explain land-use changes over time, and unlike Kappa it does not inflate results for simulations where little change takes place over time.
Publication http://library.wur.nl/WebQuery/wurpubs/406442
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Persistent Identifier urn:nbn:nl:ui:32-406442
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Repository Wageningen University & Research Centre

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