DEXi type tools

DEXi enables multi-criteria decision trees to be designed in a transparent and participative way, with weightings to take into account the expertise and/or preferences of stakeholders. As the models are qualitative, they can be used ex post (diagnosis of situations) or ex ante (choice between several options, in particular between several innovations).
These trees are hierarchical structures which represent the decomposition of the decision problem into sub-problems, which are less complex and therefore less difficult to solve than the complete problem. Each sub-problem is then represented by an evaluation criterion or input criterion (‘leaf of the tree’) given a qualitative value (of the ‘low’, “medium” or ‘high’ type). However, some input criteria are quantitative (e.g. yield) and the classes for these quantitative criteria can be defined using threshold values (Figure 2). The IZI-EVAL tool can be used to generate these threshold values (based on Agrosyst data).

Figure 2: Discretization of quantitative results into qualitative classes (Source: DEXifruits user guide)

Aggregated criteria (nodes of the tree), located upstream of these input criteria, gradually combine the information contained in the lower-level criteria on which they depend, according to a weighting reflecting their importance, until they reach a single evaluation criterion enabling a synthetic judgement to be made. Aggregations are carried out for each criterion using "utility functions", which take the form of tables filled in by experts using qualitative reasoning of the "if-then" type, such as:
IF <criterion 1 is very low> AND IF <criterion 2 is low to medium> THEN <aggregated criterion is very low>
When they are used in several places in the same tree, the criteria (input or aggregated) are said to be "linked".

DEXi has been used, among other things, in the fields of pharmacy and medicine and, since the early 2000s, to build models and decision-making tools for agricultural issues: assessing the sustainability of innovative systems in different production sectors, designing meadows with varied flora, estimating the biotic pressure on a crop, choosing tillage strategies, etc.

Tutorial to come

The IZI-Eval tool can be used to perform statistical analyses to assess the sensitivity of DEXi models to input criteria. This makes it possible to optimise their structuring and determine the level of precision required for the input data.

For further information and downloads

• Frédérique Angevin, Gabriele Fortino, Christian Bockstaller, Elise Pelzer, Antoine Messean. Assessing the sustainability of crop production systems: Toward a common framework?. Crop Protection, 2017, 97, pp.18-27. (10.1016/j.cropro.2016.11.018). (hal-01572165)
• Damien Craheix, Jacques-Eric Bergez, Frédérique Angevin, Christian C. Bockstaller, Marko Bohanec, et al.. Guidelines to design models assessing agricultural sustainability, based upon feedbacks from the DEXi decision support system. Agronomy for Sustainable Development, 2015, 35 (4), pp.1431-1447. (10.1007/s13593-015-0315-0). (hal-01173366)
• Damien Craheix, Frédérique Angevin, Jacques ‐ Eric Bergez, Christian C. Bockstaller, Bruno B. Colomb, et al.. MASC 2.0, un outil d'évaluation multicritère pour estimer la contribution des systèmes de culture au développement durable. Innovations Agronomiques   , 2012, 20, pp.35 - 48. (10.17180/bx81-1x20). (hal-02265455)
• Damien Craheix, Frédérique Angevin, Jacques ‐ Eric Bergez, Christian C. Bockstaller, Bruno Colomb, et al.. Multicriteria assessment of the sustainability of cropping systems: A case study of farmer involvement thanks to the MASC model. Xth European IFSA Symposium, Jul 2012, Aarhus, Denmark. (hal-01359797)
• Damien Craheix, Frédérique Angevin, Jacques-Eric Bergez, Christian C. Bockstaller, Bruno B. Colomb, et al.. MASC, a model to assess the sustainability of cropping systems: Taking advantage of feedback from first users. 12th congress of the European Society for Agronomy, Aug 2012, Helsinki, Finland. 2012. (hal-01359790)
• Antoine Messean, Elise Lô-Pelzer, Christian C. Bockstaller, Claire Lamine, Frédérique Angevin. Outils d’évaluation et d’aide à la conception de stratégies innovantes de protection des grandes cultures. Innovations Agronomiques, 2010, 8, pp.69-81. (10.17180/28re-fr04). (hal-01173190)
• Josephine Peigné, Vincent Lefevre, Damien Craheix, Frédérique Angevin, Mathieu Capitaine. Évaluation participative de prototypes de systèmes de culture combinant agriculture de conservation et agriculture biologique. Cahiers Agricultures, 2015, 24 (2), pp.134-141. (10.1684/agr.2015.0737). (hal-02065931)
• Elise Pelzer, Gabriele Fortino, Christian C. Bockstaller, Frédérique Angevin, Claire Lamine, et al.. Assessing innovative cropping systems with DEXiPM, a qualitative multi-criteria assessment tool derived from DEXi. Ecological Indicators, 2012, 18, pp.171-182. (10.1016/j.ecolind.2011.11.019). (hal-01019370)
• Walid Sadok, Frédérique Angevin, Jacques-Eric Bergez, Christian Bockstaller, Bruno Colomb, et al.. MASC, a qualitative multi-attribute decision model for ex ante assessment of the sustainability of cropping systems. Agronomy for Sustainable Development, 2009, 29 (3), pp.447-461. (10.1051/agro/2009006). (hal-00886501)
• Walid Sadok, Frédérique Angevin, Jacques-Eric Bergez, Christian C. Bockstaller, Bruno Colomb, et al.. Ex ante Assessment of the Sustainability of Alternative Cropping Systems: Implications for Using Multi-criteria Decision-Aid Methods - A Review. Sustainable Agriculture, Springer, 2009, 978-90-481-2665-1. (hal-01173743)