An Introductory Overview
to Multi Criteria
Evaluation
GEOG 5161: Research Design
Professor Kenneth E. Foote
Petra Norlund
2010
Outline
Introduction and Background
Definitions
What is multi criteria evaluation?
How and when is it useful?
How does it work? Case study to show
how it is implemented
• Pros and cons of the method.
• Why should we use it?
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Kärt barn har många
namn...
Multi Criteria Analysis
Multi Criteria Evaluation (MCE)
Multi Criteria Preference Analysis
Multi Criteria Decision Making
Multi Objective Evaluation
These methods are essentially one and the
same!
MCE = Multi-criteria evaluation is primarily concerned with
how to combine the information from several criteria to form a
single index of evaluation
Introduction
• Land is a scarce resource:
• Identifying suitability for
•Where to build a dam
• Water flow
• Mountainous?
• Where to place a hospital
• Costs
• Access
• Greatest need
• Criteria can be based on human or physical
geography factors
Background
• Early methods (pre computers):
• Ian McHarg (1969) Design with Nature
• Used for suitability analysis
• Tracing paper overlays
• Limited to simple Boolean analysis: AND,
OR, NOT
See demo!
Post computers: Basic GIS
Approaches
• Polygon overlay (Boolean logic)
Example uses:
• Nuclear waste
disposal sites
• Street routing
Definitions
• Decisions: a choice between alternatives
• Criterion: some basis for a decision. Two main classes:
•Factor: enhances or detracts from the suitability of a land
use alternative (e.g. distance from a road)
•Constraint: limits the alternatives
• Goal or target: some characteristic that the solution must
possess (a positive constraint)
The Basics
What is it used for?
• Decision making
• Dispute resolution
• Water resource management
• Sustainable development
• etc
Principles of MCE
• Methodology:
1. Determine criteria
(factors/constraints) to be included
2. Determining the weights for each
factor
3. Sensitivity analysis of results
1st Step: Determine the
criteria to be included
• Criteria determine the alternatives
• Oversimplification of the decision problem could
lead to too few criteria being used
• Using a large number of criteria reduces the
influence of any one criteria
• Often proxies must be used since the criteria of
interest may not be determinable
Example: Case study of a
suitable dam and reservoir
site
Criteria used:
 River
 Urban
 Forest
 Accumulated water flow
 Existing reservoir
 Watershed boundary
 City
 Hydraulic head
 Undulation
Determine the weights
• A decision is the result of a comparison of one
or more alternatives with respect to one or more
criteria that we consider relevant for the task at
hand.
• Among the relevant criteria we consider some as
more important and some as less important;
this is equivalent to assigning weights to the
criterion according to their relative importance.
2nd stage, assigning weights
Weights assigned using
AHP
Weights assigned using the
Rank Order method
Sensitivity analysis
→ sensitivity analysis: vary the
scores/weights of the factors to determine
the sensitivity of the solution to minor
changes
• Choice of criteria (e.g. why included?)
• Assesses the reliability of data: how stable is
the final result?
• Choice for weighting factors is subjective
• Will the overall solution change if you use
other weighing factors?
MCE – pros and cons
•Cons:
• Dynamic problems
strongly simplified into a
linear model
•Pros:
• Gives a structured and
traceable analysis.
• Static, lacks the time
dimension
• Possibility to use different
evaluation factors makes it
a good tool for discussion.
• Controversial method –
too subjective?
• Copes with large amounts
of information.
• It works!
Conclusion
 Good for any complex decision
problem.
 Allows decision makers to show their
thinking.
 Useful in any GIS analysis where
several criteria are incorporated.
 Includes the ability to weigh criteria.
 Often used for land allocation.