The article by Nick Black discusses the importance of observational studies in evaluating the effectiveness of healthcare interventions, challenging the notion that randomized controlled trials (RCTs) are the sole or best method. Black argues that RCTs have limitations, such as being unnecessary, inappropriate, impossible, or inadequate in certain situations. Observational studies, on the other hand, can provide valuable insights into the effectiveness of healthcare interventions, especially when RCTs are not feasible. The author highlights several scenarios where observational studies are necessary, including when interventions have dramatic effects, rare adverse outcomes, long-term consequences, and when the intervention's effectiveness depends on the subject's participation. Black also addresses practical obstacles to conducting RCTs, such as clinician refusal, ethical concerns, political and legal barriers, contamination between treatment groups, and poor patient recruitment. He emphasizes that while RCTs have methodological strengths, they cannot meet all the needs of patients, practitioners, managers, and policymakers. Observational studies, he argues, should be seen as complementary to RCTs, each offering unique contributions to the evaluation of healthcare interventions. The article calls for a balanced approach, where researchers strive for scientific rigor regardless of the method used, and both types of studies are valued for their complementary roles in advancing healthcare evidence.The article by Nick Black discusses the importance of observational studies in evaluating the effectiveness of healthcare interventions, challenging the notion that randomized controlled trials (RCTs) are the sole or best method. Black argues that RCTs have limitations, such as being unnecessary, inappropriate, impossible, or inadequate in certain situations. Observational studies, on the other hand, can provide valuable insights into the effectiveness of healthcare interventions, especially when RCTs are not feasible. The author highlights several scenarios where observational studies are necessary, including when interventions have dramatic effects, rare adverse outcomes, long-term consequences, and when the intervention's effectiveness depends on the subject's participation. Black also addresses practical obstacles to conducting RCTs, such as clinician refusal, ethical concerns, political and legal barriers, contamination between treatment groups, and poor patient recruitment. He emphasizes that while RCTs have methodological strengths, they cannot meet all the needs of patients, practitioners, managers, and policymakers. Observational studies, he argues, should be seen as complementary to RCTs, each offering unique contributions to the evaluation of healthcare interventions. The article calls for a balanced approach, where researchers strive for scientific rigor regardless of the method used, and both types of studies are valued for their complementary roles in advancing healthcare evidence.