group_modelling:goodnessoffit
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- | ====== Tools for Assessment of Multiple Scale Land Change Models ====== | + | ======Tools for Assessment of Multiple Scale Land Change Models====== |
- | Authors: | + | Kristina Helle, Pedro Andrade, and Edzer Pebesma |
- | =====Introduction==== | + | =====Introduction===== |
- | The complex relations between biophysical and anthropological factors generate the land change patterns of our environment. In order to study this complex phenomena, we have to rely on simulation models, for example cellular automata or agent-based models. | + | |
- | LUCC simulation models usually generate a new map given a real world map of land cover classes. | + | The complex relations between biophysical and anthropological factors generate the land change patterns of our environment. In order to study this complex phenomena, we have to rely on simulation models, for example cellular automata or agent-based models. LUCC simulation models usually generate a new map given a real world map of land cover classes. In the figure below, the left map shows the real data and the right one the simulated results. |
- | In the figure below, the left map shows the real data and the right one the simulated results. | + | |
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Goodness-of-fit tests compare the predicted map with the reality at the new time. | Goodness-of-fit tests compare the predicted map with the reality at the new time. | ||
- | Some authors have been proposed ways to calculate metrics trying to inform the quality of the results to the scientist. | + | Some authors have been proposed ways to calculate metrics trying to inform the quality of the results to the scientist. |
With these metrics, it is possible to calibrate or to validate the model. | With these metrics, it is possible to calibrate or to validate the model. | ||
In fact, the final objective of these goodness-of-fit methods is to point out how to improve the model. | In fact, the final objective of these goodness-of-fit methods is to point out how to improve the model. | ||
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=====State of the Art===== | =====State of the Art===== | ||
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+ | Pontius (2002) realized that we only need to take into account the cells that have changed, instead of comparing the whole maps. His more flexible approach allows to explicitly separate errors of quantity and of location and to use fuzzy classification. Later (Pontius et al. 2008) he refines his technique to compare real changes and predicted changes. Others like Jantz and Goetz (2005) did also address geometric porperties of the land use patterns like number and shape of clusters and length of edges. Some of these metrices are already implemented in TerraME but have not been used for testing. | ||
- | Pontius | + | Scale (here in terms of resolution and extend) is an important property |
- | Land use changes may show varying behaviour on different scales. Therefore it can be useful | + | Calibration of cellular automata or agent-based models is not a trivial task as parameters influence is in most cases non-linear and often the number of parameters is high, making comprehensive evaluation of all combinations unfeasible. Simple approaches like by Clarke et al. (1998) generate lots of simulations |
- | Jantz and Goetz (2005) apply several | + | |
+ | The diversity of LUCC models may require different calibration and validation methods. An overview over current models is given by Agarwal et al., a comparison of several models by Pontius et al. (2008). Parker et al. (2003) focus on multi-agent models only. | ||
=====Topics of the proposed Thesis and Questions to be answered in each work package===== | =====Topics of the proposed Thesis and Questions to be answered in each work package===== | ||
The following open questions can be investigated by a PhD and a Master theses (Supervisors: | The following open questions can be investigated by a PhD and a Master theses (Supervisors: | ||
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====Goodness of fit tests==== | ====Goodness of fit tests==== | ||
- | “Qualitatively, | + | “Qualitatively, |
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===Multi-scale=== | ===Multi-scale=== | ||
- | A current challenge in LUCC is to develop multi-scale models. Human behaviour can only be captured at different levels. Jantz and Goetz (2005) compared goodness-of-fit tests on different resolutions. But they did not address multi-scale models like the partially hierarchical model of Moreira et al. (2009), where the scale below is a finer grid of only a sub-area of the upper scale. | + | A current challenge in LUCC is to develop multi-scale models. Human behaviour can only be captured at different levels. Jantz and Goetz (2005) compared goodness-of-fit tests on different resolutions. But they did not address multi-scale models like the partially hierarchical model of Moreira et al. (2009), where the scale below is a finer grid of only a sub-area of the upper scale. |
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====Calibration and Validation==== | ====Calibration and Validation==== | ||
- | To complete the design of a model calibration and final validation is needed. Both procedures require goodness-of-fit tests. Calibration should improve the most sensitive and important parameters. Validation finally tests if the calibrated model is overfitting the data or to which extent it is valid. | + | To complete the design of a model calibration and final validation is needed. Both procedures require goodness-of-fit tests. Calibration should improve the most sensitive and important parameters. Validation finally tests if the calibrated model is overfitting the data or to which extent it is valid. |
- | Up to now, models in TerraME are not calibrated statistically but by expert advice. This expertise could be used together with Monte Carlo simulations to find the sensitive parameters. | + | Up to now, models in TerraME are not calibrated statistically but by expert advice. This expertise could be used together with Monte Carlo simulations to find the sensitive parameters. |
Top-down models are easier to calibrate than bottom-up models as in the former demand (amount of change) and allocation can be separated. | Top-down models are easier to calibrate than bottom-up models as in the former demand (amount of change) and allocation can be separated. | ||
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The first step is to implement Costanza' | The first step is to implement Costanza' | ||
- | The results of goodness of fit tests may be simple numbers but often are curves or maps and probability distributions. | + | The results of goodness of fit tests may be simple numbers but often are curves or maps and probability distributions. |
These results must be communicated e.g. by visualization in a way that supports the usability of the models. The most important properties should have an easy interpretation and access. On the other hand, experts should be able to improve the model by thoroughly investigating the errors. | These results must be communicated e.g. by visualization in a way that supports the usability of the models. The most important properties should have an easy interpretation and access. On the other hand, experts should be able to improve the model by thoroughly investigating the errors. | ||
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=====Mobility Measures===== | =====Mobility Measures===== | ||
The topic is at the overlap of the research at INPE (agent-based and cellular automata models of LUCC) and IFGI (statistics, | The topic is at the overlap of the research at INPE (agent-based and cellular automata models of LUCC) and IFGI (statistics, | ||
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===== References ===== | ===== References ===== | ||
+ | AGARWAL, CH.; GREEN, G. M.; GROVE, J. M.; EVANS, T. P. & SCHWEIK, CH. M. [[http:// | ||
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C. M. ALMEIDA, A. M. V. MONTEIRO, G. CAMARA, B. S. SOARES-FILHO, | C. M. ALMEIDA, A. M. V. MONTEIRO, G. CAMARA, B. S. SOARES-FILHO, | ||
BOX, G. E. P. {{http:// | BOX, G. E. P. {{http:// | ||
+ | |||
+ | CANDAU, J., 2002, {{group_modelling: | ||
+ | Masters thesis, Department of Geography, University of California. | ||
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+ | CLARKE, K.; HOPPEN, S. & GAYDOS, L. (1998): {{http:// | ||
COSTANZA, R. {{encontros_e_eventos: | COSTANZA, R. {{encontros_e_eventos: | ||
- | JANTZ, C. A.; GOETZ, S. J. {{group_modelling: | + | HAKAN, O.; KLEIN, A.G.; SRINIVASAN, R. (2007): |
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+ | JANTZ, C. A.; GOETZ, S. J. {{group_modelling: | ||
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+ | KOK, K. & VELDKAMP, A. {{group_modelling: | ||
+ | analysis in Central America}}. Agriculture, | ||
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+ | LI, B.-L. 2000. {{group_modelling: | ||
MANSON, S. M. {{encontros_e_eventos: | MANSON, S. M. {{encontros_e_eventos: | ||
Problems, Prospects and Research Needs. Banff, Alberta, Canada, September 2 - 8, 2000. | Problems, Prospects and Research Needs. Banff, Alberta, Canada, September 2 - 8, 2000. | ||
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+ | MILLER, J. H. 1998. {{group_modelling: | ||
+ | simulation models}}. Management Science 44 (6): 820–30. | ||
E. MOREIRA, S. COSTA, A. P. AGUIAR, G. CAMARA, T. CARNEIRO Dynamic coupling of multiscale land change models: interactions and feedbacks across regional and local deforestation models in the Brazilian Amazonia, Ecological Modelling (// | E. MOREIRA, S. COSTA, A. P. AGUIAR, G. CAMARA, T. CARNEIRO Dynamic coupling of multiscale land change models: interactions and feedbacks across regional and local deforestation models in the Brazilian Amazonia, Ecological Modelling (// | ||
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+ | PARKER, D. C.; Manson, S. M.; JANSSEN, M. A.; HOFFMANN, M. J. & DEADMAN, P. 2003 {{group_modelling: | ||
+ | and Land-Cover Change: A Review}}. Annals of the Association of American Geographers 93 (2): 314–337. | ||
PONTIUS, R. G. {{encontros_e_eventos: | PONTIUS, R. G. {{encontros_e_eventos: | ||
Vol. 68, No. 10, October 2002, pp. 1041–1049 | Vol. 68, No. 10, October 2002, pp. 1041–1049 | ||
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+ | PONTIUS, R.G.; BOERSMA, W.; CASTELLA, J.-CH.; CLARKE, K.; DE NIJS, T.; DIETZEL, CH.; DUAN, Z.; FOTSING, E.; GOLDSTEIN, N.; KOK, K.; KOOMEN, E.; LIPPIT, CH. D.; MCCONNELL, W.; SOOD, A. M.; PIJANOWSKI, B.; PITHADIA, S.; SWEENEY, S.; TRUNG, T. N.; VELDKAMP, A. T. & VERBURG, P. H. {{group_modelling: | ||
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+ | ROGERS, A.; VON TESSIN, P. (2004): | ||
+ | |||
+ | WU, F., 2002, {{group_modelling: | ||
+ | pp. 795–818. | ||
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+ | ==related literature== | ||
+ | GILES, R. H., Jr. & TRANI, M. K..1999. {{http:// | ||
group_modelling/goodnessoffit.1237489350.txt.gz · Última modificação: 2009/03/19 19:02 por inpeifgi