Introduction to Multi Criteria Analysis MCA Multi Criteria

Multi Criteria Analysis • MCA: aims to rank alternative strategies when the effect of

Multi Criteria Analysis • Steps: – – – – Generation of alternatives Formulation of

Multi Criteria Analysis • Approaches: – Weighted sum method – Pairwise comparison (concordance index)

Multi Criteria Analysis • Weighted Sum: Wt. Alt. A Alt. B Criterion 1 1

MCA Example The following table include some data about the different technologies for brackish

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Introduction to Multi Criteria Analysis MCA

Multi Criteria Analysis • MCA: aims to rank alternative strategies when the effect of these strategies cannot be translated into one single measuring scale • Score card: represent the impacts of alternative strategies on criteria Wt. Alt. 1 Alt. 2 Alt. 3 Criterion 1 1 good v. good bad Criterion 2 2 +++ 0 -- Criterion 3 1. 5 5. 5 9 2 Criterion 4 2 - 0. 3 + 0. 5 Criterion 5 3 20, 000 50, 000 30, 000 ? ? ? Total score

Multi Criteria Analysis • Steps: – – – – Generation of alternatives Formulation of criteria Filling score card Standardization of scores Application of weights Ranking of Alternatives Sensitivity analysis • 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

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:

Multi Criteria Analysis • Weighted Sum: Wt. Alt. A Alt. B Criterion 1 1 0. 9 0. 2 Criterion 2 2 0. 4 0. 7 Criterion 3 2 0. 4 0. 6 2. 5 2. 8 Wtd Sum • Concordance : – Concordance index: KAB = to what degree alt A is better than alt B KAB = 1 (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)

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 ? ? Wt. Brackish EDR Brackish RO Barckish IX capital cost 130000 100, 000 110000 O&M cost ($/m 3) 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 availability of membranes and chemicals -1 -3 -2 moderate high low Criteria