Pair-matching in randomized controlled trials (RCTs) has received increased attention in criminology, the social sciences more generally, and medicine and public health, with a growing body of research demonstrating the design's benefits over “simple” RCTs. We carry out a review of matched-pair RCTs compared with simple RCTs to address a somewhat provocative yet fair question for evaluation research on crime and violence prevention interventions: Is it time for the use of pair-matching in all RCTs? At the heart of this question is the ability of the design to most efficiently and robustly compare like with like, thereby, improving confidence in observed effects of intervention trials. Several key findings emerge from the review. First, it is inadequate to examine or discuss RCTs as a single, uniform evaluation design. Here, the key organizing construct is the unit of allocation: individuals; groups of individuals (or clusters); and geographical places. Second, the advantages vastly outweigh the disadvantages for the use of matched-pair RCTs compared to simple RCTs, and most of the advantages hold for all three units of allocation. Third, pair-matching can be used with rather small samples (≥6 units) in cluster-based trials without compromising statistical power or degrees of freedom; less is known about individual- and place-based trials. Fourth, pair-matching cannot be used with some types of RCTs (e.g., cross-over) and is less amenable in other contexts (e.g., RCTs that enroll and randomize individuals on a rolling basis). Implications for evaluation research and public policy are discussed.

随机对照试验 (RCT) 中的配对在犯罪学、更广泛的社会科学以及医学和公共卫生领域受到越来越多的关注，越来越多的研究表明该设计相对于“简单”RCT 的优点。我们对配对随机对照试验与简单随机对照试验进行了比较，以解决犯罪和暴力预防干预措施评估研究中一个有点挑衅但公平的问题：现在是在所有随机对照试验中使用配对配对的时候了吗？这个问题的核心是设计是否能够最有效、最稳健地进行同类比较，从而提高对干预试验观察到的效果的信心。审查得出了几个关键发现。首先，将随机对照试验作为单一、统一的评估设计进行检查或讨论是不够的。在这里，关键的组织结构是分配单位：个人；个体群体（或集群）；和地理位置。其次，与简单的随机对照试验相比，使用配对随机对照试验的优点远远超过缺点，并且大多数优点对于所有三个分配单位都适用。第三，在基于聚类的试验中，可以对相当小的样本（≥6个单位）使用配对匹配，而不会影响统计功效或自由度；关于基于个人和地点的试验知之甚少。第四，配对匹配不能与某些类型的随机对照试验（例如交叉）一起使用，并且不太适合在其他情况下使用（例如，在滚动的基础上招募和随机化个体的随机对照试验）。讨论了对评估研究和公共政策的影响。