“It is the position of this Task Force that rigorous well designed and well executed Observational Studies (OS) can provide evidence of causal relationships” [1]. All flows from this carefully crafted statement in the middle of the ISPOR Good Research Practices Task Force Report, which provides a well-reasoned and well-conceived summary of the potential role in comparative effectiveness research (CER) of observational studies, and especially of prospective studies—ones that collect information. But the conceptual basis for the value of OS and the principles articulated would lack compelling interest if fulfilling the goals of CER did not force us to make use of OS, and, in doing so, bring OS as close to parity as possible with randomized controlled trials (RCTs).

The implication of this task force review article is that the question of RCTs versus OS should be reframed: Can conclusions from OS studies, if optimized (“rigorous, well-designed and well-executed”), be used, at approximately the same level of the hierarchy of quality, hopefully in conjunction with RCTs, in systematic reviews to inform clinical practice guidelines and policymakers about the effectiveness of medical practices.