However, as the number of isotopic contrasts considered in an experimental dataset was reduced, there was an impact on the relative evidence for "more complex" models. This is in agreement with the perceived wisdom of reflectometry, that a more complex analytical model may be applied when there is a greater number of isotopic contrasts present in the dataset. Furthermore, it matches well with early work in the field where simple models were applied to datasets with few isotopic measurements . It was also shown that if partial deuteration was not possible, and therefore only the d 83 -ACMW, d 83 -D 2 O, and h-D 2 O may be measured, the greatest evidence was for model 1, which can be attributed to the lack of definition that is provided by isotopic contrast labelling. This indicates the substantial effect that the collected data may have on the model that can be used in the experimental analysis, suggesting that one-size-fits-all analytical models may not be possible for the analysis of reflectometry data from Langmuir-Blodgett monolayers. We hope that this will inspire those analysing any reflectometry data to more readily consider the relative evidence of particular models. Finally, we accept that if a full model comparison is not performed, or if the results are overlooked, then this may be done based on a qualitative understanding of the experimental system, despite not being demonstrated fully by the analysed data.