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Guide to COST-BENEFIT ANALYSIS of investment projects - Ramiri

Guide to COST-BENEFIT ANALYSIS of investment projects - Ramiri

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4.2.6 Risk assessmentThe risk assessment is shown here on the <strong>investment</strong> costs, which emerged as one <strong>of</strong> the critical variablesin the sensitivity test. The risk assessment has been carried out for the Option 2. Given the lack <strong>of</strong> reliablepast data on similar <strong>investment</strong>, a three point distribution has been assumed, with the following range <strong>of</strong>values: a high estimate in which the <strong>investment</strong> costs are three times higher than the estimated ‘best guessvalue’, and a lower value in which the <strong>investment</strong> costs are 10% lower than the ‘best guess value’. Thishighly pessimistic assumption is based on his<strong>to</strong>rical data, which show a tendency <strong>to</strong>wards a systematicoptimism bias in railway <strong>investment</strong>. Given the range <strong>of</strong> values adopted, the result is an asymmetrictriangular probability distribution.Figure 4.4 Probability distribution <strong>of</strong> <strong>investment</strong>s costs. Triangular (0.9; 1; 3)10.90.80.70.60.50.40.30.20.10X

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