2.3.3. Assessment of the Tool to Criteria Weights and Data Variation

Following the assessment of the influence of the different methodologies integrated into the tool, an assessment of rank stability was conducted by accounting for weight factors and data value variations. To this end, a series of indicative weighting scenarios were considered for which smaller and larger adjustments have been made with respect to the applied weights as derived from the AHP analysis. In addition, a thorough sensitivity analysis with respect to the data value variation has been conducted. In order to test the sensitivity of the method to small changes in the values of the original data, 1000 samples were simulated by perturbing the original data by a random error. It is assumed that the errors follow a normal distribution with zero mean and standard deviation proportional to the standard deviation of the corresponding indicator of the initial data. Each of these samples was ordered according to the values of the overall sustainability index, and the mean ranking for each material, as well as the standard deviation, was calculated. All the simulations are implemented in R version 4.1.1 [50].
