5.19. In order to demonstrate compliance with a numerical measure or standard of performance, it may be appropriate to undertake a conservative analysis based on relatively simple models. Such an approach will be feasible if there is a large margin of safety. Caution is necessary, however, because, if misused, results from overly conservative or worst case representations of the disposal system may lead to poor decision making that is based on assessment results that bear little resemblance to the actual performance of the facility. In addition, the use of an overly conservative approach can raise concerns of interested parties about manipulation of results, if later assessments adopt a more realistic (or less conservative) approach to demonstrate compliance with regulatory requirements. In order to avoid such situations, the choice of a conservative approach or a realistic approach, and the reasons for modifying the approach if this is done, should be clearly documented and communicated.