One important advantage of IAST is that we do not need to fit the data, while DSL does depend on how the data are fitted. In figure we illustrate the effect of the fitting procedure on the ranking. These figures show that DSL tends to give a higher purity than DSL Henry , but this does not hold for all structures. : Materials ranking in terms of purity of the output stream for a coal-fired power plant (CF-PP), natural gas-fired power plant (NG-PP), and confined spaces (CS). In these figures, we compare DSL with DSL Henry , see also the caption to figure .