Bärnighausen Till, Røttingen John-Arne, Rockers Peter, Shemilt Ian, Tugwell Peter
Heidelberg Institute of Public Health, Heidelberg University, Heidelberg, Germany; Harvard T.H. Chan School of Public Health, Boston, USA; Africa Health Research Institute, KwaZulu-Natal, South Africa.
Harvard T.H. Chan School of Public Health, Boston, USA; Norwegian Institute of Public Health, Oslo, Norway.
J Clin Epidemiol. 2017 Sep;89:4-11. doi: 10.1016/j.jclinepi.2017.02.020. Epub 2017 Jul 8.
The objective of this study was to contrast the historical development of experiments and quasi-experiments and provide the motivation for a journal series on quasi-experimental designs in health research.
A short historical narrative, with concrete examples, and arguments based on an understanding of the practice of health research and evidence synthesis.
Health research has played a key role in developing today's gold standard for causal inference-the randomized controlled multiply blinded trial. Historically, allocation approaches developed from convenience and purposive allocation to alternate and, finally, to random allocation. This development was motivated both by concerns for manipulation in allocation as well as statistical and theoretical developments demonstrating the power of randomization in creating counterfactuals for causal inference. In contrast to the sequential development of experiments, quasi-experiments originated at very different points in time, from very different scientific perspectives, and with frequent and long interruptions in their methodological development. Health researchers have only recently started to recognize the value of quasi-experiments for generating novel insights on causal relationships.
While quasi-experiments are unlikely to replace experiments in generating the efficacy and safety evidence required for clinical guidelines and regulatory approval of medical technologies, quasi-experiments can play an important role in establishing the effectiveness of health care practice, programs, and policies. The papers in this series describe and discuss a range of important issues in utilizing quasi-experimental designs for primary research and quasi-experimental results for evidence synthesis.
本研究的目的是对比实验和准实验的历史发展，并为关于健康研究中准实验设计的期刊系列提供动力。
一篇简短的历史叙述，包含具体实例，并基于对健康研究实践和证据综合的理解进行论证。
健康研究在制定当今因果推断的金标准——随机对照多重盲法试验方面发挥了关键作用。从历史上看，分配方法从便利分配和目的分配发展到交替分配，最终发展到随机分配。这一发展既受到对分配中操纵问题的关注推动，也受到统计学和理论发展的推动，这些发展证明了随机化在为因果推断创造反事实方面的力量。与实验的循序渐进发展不同，准实验起源于非常不同的时间点，源于非常不同的科学视角，并且在其方法学发展过程中经常出现长时间中断。健康研究人员直到最近才开始认识到准实验在产生关于因果关系的新见解方面的价值。
虽然在为临床指南和医疗技术监管批准生成所需的疗效和安全性证据方面，准实验不太可能取代实验，但准实验在确立医疗保健实践、项目和政策的有效性方面可以发挥重要作用。本系列论文描述并讨论了在利用准实验设计进行初步研究以及利用准实验结果进行证据综合方面的一系列重要问题。
