Quantifying these variables are much complex and therefore the parameter uncertainty is high. In some cases, the variable cannot be measured directly and there is a need to expert judgment to CHALMERS, Product and Production Development, Master’s thesis 2011 11
determine value for parameters. Therefore, parameter uncertainties include not only vagueness due to the recorded data, but also uncertainties inexperts’ judgments of parameter values in case this data are not at hand (Veselyet al., 1984; Willows et al., 2003; WHO, 2008; NRC, 2009). Variable uncertainties arise because of (WHO, 2008;Lioy, 2002)