There is little doubt that evidence-based principles have changed the way we think about clinical practice. However, there are challenges to clinical decision making that evidence alone cannot answer. Challenges include realities such as research populations not reflecting “real-world” application, inconsistent adherence to evidence-based principles within clinical practices, sophisticated decision rules overshadowing clinical experience, and gaps in care that impact outcomes. This article attempts first to demonstrate caveats of using and interpreting evidence-based principles and, second, to illustrate common evidence-based concepts which many clinicians misunderstand. These include the cascade effect, common risk difference measures, and predictive values.