The key features of DecernsSDSS are presented in the sections 1, 2 and 3.
DecernsSDSS can be effectively used by the following (potential) users:
- State and regional departments/centers, business companies, and individual experts responsible or involved in decision-making process on land-use planning/management, remediation of contaminated sites, monitoring and environmental protection;
- Centers and experts, working with GIS, decision analysis, Web-technologies, and risk evaluation and management in different scientific and applied fields;
- Educational, specialized and training centers working with IT and risk analysis;
- Software developers.
1 The features of DecernsSDSS
The DecernsSDSS features indicated below emphasize key differences of this SDSS from other GIS/MCDA systems:- DecernsSDSS is an MCDA-oriented SDSS (software) which includes several basic and advanced multi-criteria decision analysis methods and tools, coupled with GIS-functions for map layer processing and spatial data analysis and visualization;
- MCDA and GIS subsystems may be used independently;
- extended uncertainty analysis based on realization of sensitivity analysis and implementation of probabilistic methods and fuzzy sets can be used within the decision-making process;
- case/site-specific models can be integrated with DecernsSDSS through the models provider;
- specific tools allow the creating and handling a set of spatial alternatives along with transferring map and criteria data to the performance table; this is very effective in the case of a large number of alternatives for subsequent multi-criteria analysis;
- DecernsSDSS is a web-based distributed SDSS, developed with the use of up-to-date open source technologies, which effectively can be used in Internet/Intranet;
- the architecture of DecernsSDSS is easily extendible through adding new MCDA methods and tools, GIS or SDSS functions, as well as a set of site-specific models within the SDSS customization.
2 DecernsSDSS: the main components
The Application Programming Interface of DecernsSDSS integrates the three main components of SDSS onto a single platform:- GIS-subsystem,
- MCDA-subsystem,
- and Models.
3 DecernsSDSS: the main methods and functions
The functionality of DecernsSDSS is based on application of the following functions, methods and tools.3.1 GIS Functions
The GIS subsystem is designed to have all of the basic GIS features, including:
- multi-layered vector and raster map visualizations, and coloring;
- editing legends;
- zooming and panning;
- measurements (distance along line or polylines, polygon area);
- features selection (single and multi select) and searching;
- map attributes viewing and editing;
- statistical analysis of attributes;
- buffering;
- overlays, including union, intersection, and subtraction of cartographic layers;
- rasterization (conversion of vector to raster maps);
- scalar operations (map math such as addition, subtraction, and multiplication);
- spatial interpolation (inverse distance weighting), and geostatistics;
- support of different cartographic projects; and
- support of all common GIS map formats.
3.2 MCDA-based Decision Support Methods and Tools
A key component of the DecernsSDSS is the decision support subsystem, which is based on the implementation of MCDA methods and associated tools. The following multi-criteria methods and tools are used in the DecernsSDSS (details of these methods can be found in (Keeney & Raiffa, 1976; Belton & Stewart, 2002; Figueira, 2005; Malczewski, 1999; Tervonen & Figueira, 2008); (brief description of the used methods is presented in the chapter 4):
Basic discrete multicriteria/MADM methods such as
- MAVT (Multi-Attribute Value Theory);
- AHP (Analytic Hierarchy Process);
- TOPSIS (Technique for Order Preference by Similarity to the Ideal Solution); and
- PROMETHEE (Preference Ranking Organization METHod for Enrichment Evaluations);
- MAUT (Multi-Attribute Utility Theory);
- ProMAA (Probabilistic Multi-criteria Acceptability Analysis) (Yatsalo, Tkachuk, & Gritsyuk, 2009);
- F-MAVT (Fuzzy MAVT), and
- FMAA (Fuzzy MAA), (Yatsalo, Gritsyuk, et.al, 2009), where fuzzy criterion values and weights may be used);
The following tools are also used within the MCDA-subsystem:
- Value Tree for problem structuring (and data input and presentation);
- Value Path for source data presentation and ranking;
- Scatter Plot for presentation of source data in 2-dimensional criteria space;
- Weight Sensitivity analysis (line weights and walking weights tools);
- Value/Utility function sensitivity analysis (for MAVT, MAUT, ProMAA, F-MAVT, FMAA methods);
- Different graphical and tabular tools for probabilistic input/output data presentation (probability and density distributions), including setting source probability distributions for criteria (MAUT, ProMAA) and weights (ProMAA) with the use of Normal, Uniform, Log-Normal and delta distributions;
- Different graphical and tabular tools for fuzzy input/output data presentation, including setting source fuzzy numbers (triangular, trapezoidal, piecewise linear, singleton) for criteria and weights (F-MAVT, FMAA).
3.3 Spatial Decision Support System
Integration of MCDA and GIS subsystems produces a SDSS/Spatial Decision Support System. SDSS tools are available for the following:
- setting spatial alternatives using the basic or created cartographic layers, querying and selecting attributive data, and highlighting the selected map objects;
- analyzing and processing cartographic maps or attributive data using GIS functions and implementing MCDA tools at each stage of the multi-criteria problem investigation;
- development of alternatives and criteria specification; any number of alternatives may be considered (e.g., all the objects of a cartographic layer or only a few objects selected by user(s) are considered as alternatives);
- automatically transferring attributes for all the alternatives into the performance table for map-based criteria within the multi-criteria problem under investigation (the values for non map-based criteria are filled manually in the performance table/value tree by SDSS user);
- highlighting the specific or selected spatial alternative(s) in the map.
- problem definition;
- structuring multi-criteria problems using value trees, and both top-down and bottom-up approaches for criteria setting;
- assessments of the alternatives against the criteria which are conducted using models, GIS tools, and expert/stakeholder judgments; generation of a performance table;
- determination of the preferences (scoring and weighting criteria by the experts/stakeholders);
- aggregation of the criteria (scores) for each alternative;
- sensitivity/uncertainty analysis;
- stakeholder review of the resulting selection/ranking/screening/sorting of alternatives;
- providing recommendations for the decision-makers (a choice, for example, of the ‘optimal’/trade-off alternative or an instruction to return and refine any of the previous steps).
