Using a Bayesian Belief Network for classifying valuation methods
By: David Barton, Anita Bayer, Diana Tuomasjukka, Genevieve Patenaude, James Paterson,
Martin Karlsen and Anders L Madsen
November 4, 2016
Highlights
Bayesian Belief Networks (BBNs):
organise expert judgement on valuation method characteristics
used as an expert system classification tool
capture fuzzy expert judgement can be represented using probabilities
show methods relative likelihoods of satisfying criteria instead of binary yes/no
show portfolios of methods satisfying multiple-selection criteria
ideal for identifying method complementarity
can be used to easily validate method classification by third parties
Introduction
Oppla is an online platform offering advice on selection of ecosystem service appraisal methods. This note demonstrates the use of a Bayesian belief network (BBN) as an expert system to support method selection.
Data
The BBN is populated with method characteristics collected from ecosystem service assessment and valuation practitioners initially in OpenNESS. This was then extended to encompass also Operas methods for the purposes of Oppla. The templates build on previous methodological expertise which has been shared and tested with case studies during several training occasions organized within OpenNESS (January 2014: MCDA, April 2014: non-monetary methods, October 2014: monetary methods and mapping & modelling tools). The templates also underwent an internal reviewing process. Templates were commented by two reviewers, one having an in-depth knowledge of the specific methodological approach and another one with expertise in other methodological fields, to collect both insider and outsider views to the templates. Templates for monetary methods were reviewed by only one expert of the field. Based on reviewers' comments the templates were checked and revised to increase clarity and coherence.
Methods were classified according to requirements and value types they
addressed. See method templates below for further details.
Download the Excel sheet with methods characteristics here
Method
The BBN was structured as a classification model where the method selected is a parent node of the classification criteria (Table 1). There are 26 method characteristics.
The network can be used in two ways.
- Model selection support mode: Open the widget panes Context, Scale Data, ES(ecosystem services), Resources, TEV and select the method characteristics that are relevant for your context. The portfolio of tools that are relevant for those conditions will be shown under Tools to the right.
- Model description mode: Open the BBN pane. Here you see the frequency distributions for all methods and their characteristics. Initially no method is selected - all show equal probabilities. To see the characteristics of a particular method, click on the green bar next to the method. Where the characteristics of the methods is uncertain/fuzzy a probability distribution is displayed.
Decision Context
Scale
Data
ES
Resources
TEV
BBN
Tools
OPERA methods
OpenNESS methods
Updating the method characteristics in the model
The correlations of the methods classification model have been quantified using a CSV file corresponding to a Data Matrix similar to the one shown in Figure 1.
It is possible to change the methods characteristics using your own Data Matrix. The Data Matrix has to follow a certain format and should be uploaded as a CSV file.
The buttion below can be used to change the classification represented by the model by uploading a CSV file.
To ease the preparation of the CSV file three templates are provided (example 1, example 2 and example 3 listed below). To use one of the templates, you download the file to local disk, make the required changes and upload the file using the button above. It is important that only the values are changed (there is no test for types, spelling errors, etc). Also, if the file is not loaded correctly, then it may be necessary to use the Excel function Text to Columns under the Data tab.
Download example 1: template CSV file. Download example 2: template CSV file Download example 3 (empty file): template CSV file
Example 1 corresponds to the default version of the model created when the page is load, example 2 is created from example 1 by changing a ones to zeros and vice versa, and in example all values are deleted.
Notice that it is not possible to update the methods or the characteristics of the model. It is only possible to change the values, i.e., how the methods are classified according to requirements.
Here is the XLS file corresponding to the example 1 CSV file Download example 1: template XLS file. It is important to save this file as CSV before uploading to the web site.
The below button can be used to download the classification model to local disk such that it can be open in the HUGIN Graphical User Interface.
References
Kelemen, E., D. N. Barton, S. Jacobs, B. Martin-Lopez, H. Saarikoski, M. Termasen, G. Bela, L. Braat, R. Demeyer, M. Garcia-Llorente, E. Gomez-Baggethun, J. Hauck, H. Keune, S. Luque, I. Palomo, G. Pataki, P. Tenerilli, and F. Turkelboom. 2015. Preliminary guidelines for integrated assessment and valuation of ecosystem services in specific policy contexts. EU FP7 OpenNESS Project Deliverable 4.3., European Commission FP7.
Kjærulff, U.B and Madsen, A.L. (2013): Bayesian Networks and Influence Diagrams: A Guide to Construction and Analysis. Second Edition. Springer.
Haines-Young, R., Barton, D.N., Smith, R. and A. Madsen (2013): Bayesian Belief Networks, a cross-cutting methodology in OpenNESS: Briefing note version 2.2, 26 September 2013.
Contact information
For further details contact: David Barton @ NINA.