It is unknown what techniques were used to derive the CSI.
Given the data available, any quantitative risk analysis would likely bog down due to error and incomplete data. This means the CSI Index scale as a probability of safety scale would be all but impossible to calculate.
Any qualitative risk assessment techniques used would simply be the opinion of the assessor(s) and should be clearly identified as opinion.
By presenting a quantitative probability scale, CSI aligns it self with statistical and scientific authority… which has not been shown to be valid. Such predictive probabilistic analysis is not possible in a rigorous way with the available data.