While the results are consistent within the statistical error bars (note that r 1 has to switch place with r 2 as well) they should be equal since the same data was used. The reason for the remaining difference is the assumption of constant relative error, yielding larger errors for case B and therefore weaker constraints on the parameters. In case of constant absolute errors, both would yield the same result. Lastly it should be noted that we do not intend to question the validity of the model, equation ( ), when fitting the data used here. This question was already extensively addressed in finding that the difference for the data analysed is well within the statistical error. Our procedure is, however, completely free to use the cumulative form of the copolymer composition model (at the expense of some computational time).