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

van Vliet, J, Bregt, AK and Hagen-Zanker, A (2011) Revisiting Kappa to account for change in the accuracy assessment of land-use change models Ecological Modelling, 222. pp. 1367-1375.

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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 K-Simulation, 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 K-Simulation are compared using the results of a land-use model. It is found that only K-Simulation 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. (C) 2011 Elsevier BM. All rights reserved.

Item Type: Article
Divisions : Surrey research (other units)
Authors : van Vliet, J, Bregt, AK and Hagen-Zanker, A
Date : 2011
DOI : 10.1016/j.ecolmodel.2011.01.017
Uncontrolled Keywords : land-use change model calibration map comparison kappa statistic accuracy assessment spatial simulation-models validation maps landscape cover performance skill
Depositing User : Symplectic Elements
Date Deposited : 28 Mar 2017 13:49
Last Modified : 24 Jan 2020 12:03

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