This contribution focuses on the consideration of the uncertainties of input parameter, e.g. material, geometry and actions, within the numerical design process of a structure. Given an adequate modeling of these uncertainties using polymorphic uncertain variables, the objective here is to extract information regarding the robustness of the design from the uncertain output quantities. For this purpose, suitable information reduction measures (IRMs) are selected to quantify the designs' performance as well as its robustness. In this contribution, a detailed discussion about the different characteristics of the uncertain quantities expressed by various IRMs is given. In addition, the question of how to treat nested IRMs in case of polymorphic uncertain variables is addressed, including the investigation regarding their origin, the aleatoric and/or epistemic uncertainty of the input variables. A suggestion on how to improve the interpretability of the resulting IRMs is shown by an example of a simplified structural design process.