How Do We “Validate” a QSP Model?

This is a question that arises recurrently, both in the process of publishing Quantitative Systems Pharmacology (QSP) research – and more critically for those making drug development decisions based on model simulations. Although previous commentaries have addressed this issue, there is still no agreed-upon answer. Using the associated article by Zhu et al. as an example, I will describe how Virtual Populations can be used to assess confidence in qualitative predictions from QSP models.