1. Introduction to Multi Criteria Analysis MCA

2. Multi Criteria Decision Analysis
MCDA is both an approach and a set of techniques, with the goal of providing an overall ordering of options, from the most preferred to the least preferred option. The options may differ in the extent to which they achieve several objectives, and no one option will be obviously best in achieving all objectives.
In addition, some conflict or trade-off is usually evident amongst the objectives; options that are more beneficial are also usually more costly, for example. Costs and benefits typically conflict, but so can short-term benefits compared to long-term ones, and risks may be greater for the otherwise more beneficial options.
MCDA is a way of looking at complex problems that are characterized by any mixture of monetary and non-monetary objectives, and to present a coherent overall picture to decision makers. The purpose is to serve as an aid to thinking and decision making, but not to take the decision.

3. Steps in
Multi Criteria Analysis

4. Multi Criteria Analysis
Score card:
represents the impacts of alternative strategies on criteria
aims to rank alternative strategies when the effect of these strategies cannot be translated into one single measuring scale
Wt.
Alt.1
Alt.2
Alt.3
Criterion 1 1
good
v. good
bad
Criterion 2 2
+++ --
Criterion 3
1.5
5.5 9
Criterion 4
- 0.2
- 0.3
+ 0.5
Criterion 5 3
20,000
50,000
30,000
Total score
???

5. Multi Criteria Analysis
Weighting:
The weighting approach involves assigning a
relative weight to each objective/criteria
Cautions
Avoid double counting (e.g. groundwater level and cost of pumping)
Specification of units (negative or positive, best or worst)
Score cards represent one scenario
Score card are made for one time horizon
Be aware of uncertainties

6. Multi Criteria Analysis
Approaches:
Weighted sum method
Pairwise comparison (concordance index)
Standardization Methods
Subjective/qualitative scores can be translated into 1-10 scale
For Quantitative scores the following formula can be applied:

7. Multi Criteria Analysis
Weighted Sum:
Concordance :
Concordance index: KAB = to what degree alt A is better than alt B
KAB = (A scores better than B for Criterion 1 with weight 1)
KBA = 2+2 = 4 (B scores better than A for criteria 2 and 3)
KBA - KAB = 3 (the higher indicates the degree to which B dominates A)
Wt.
Alt.A
Alt.B
Criterion 1 1
0.9
0.1
Criterion 2 2
0.4
0.5
Criterion 3
0.6
Wtd Sum
2.5
2.3

8. MCA Example
The following table include some data about the different technologies
for brackish water purification.
We wish to select which technology is best for Gaza ??
Criteria
Wt.
Brackish EDR
Brackish RO
Barckish IX
capital cost
130000
100,000
110000
O&M cost ($/m3)
0.3
0.25
0.35
recovery rate (%)
95%
70%
97%
suitability to gaza water
moderate
high
low
quality of water (TDS)
100
150
250
environmental impacts -1 -3 -2
availability of membranes and chemicals