Lumping in reaction kinetics

In the same paper cited above, Luss Hutchinson consider the reaction 

Another interesting result of theirs is that they are able to estimate the sensitivity of the reaction rate of the lumped component with respect to changes in the original reaction rates and concentrations without knowing original reaction rate constants and initial concentrations, using nothing other than easily measurable data. 

Finally, let us mention that lumping is especially important in the presence (in the model) of continuous components (Aris, 1969 Bailey, 1972). It may be worth citing Aris (1969) here When infinitely many components are involved, a first order system may be lumped into virtually any kinetic law, and probably an approximate form of such lumping accounts for the success of some of the less enlightening empirical rate expressions.  

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