Table purposely lists k obs values determined both by the fit of reaction progress data to Eqn (4) and also by the fit of the same progress curve data to Eqn . Note that the best-fit values of are very similar to each other. A major practical significance of this result lies in that Eqn (4) as the fitting model is exquisitely sensitive to the initial estimate of model parameters v 0 , v i and k obs . Therefore it proved very beneficial to always perform all progress curve fits first to the classical rate Eqn (1) and then re-use the best-fit values of v 0 , v i and k obs so obtained as initial estimates in the fit to Eqn (4).