Objectives

When offenders or victims are randomly assigned to receive experimental vs. current treatments, the external validity of results may depend on whether different treatments are delivered by similar kinds of treatment providers. When treatment providers volunteer to deliver innovative practices in an experiment, it is unclear whether outcomes depend on the content of the treatment, enthusiasm of the providers for the new practice, or both. In such situations, the potential for what we describe as differential predisposition of volunteers for a new treatment raises a question of external validity.

Methods

We describe the process by which 14 out of 29 mediators across seven Danish police districts came to deliver a new, restorative conferencing method of conducting face-to-face meetings between offenders and their victims, in comparison to longstanding mediation methods.

Results

We negotiated with all seven District mediation leaders and all 29 of their mediators to use partial random assignment of 14 of the mediators to deliver the new, restorative model. The 14 trained providers of the new method were substantially similar in several measureable characteristics to the 15 other mediators who continued to use the preexisting model, but we cannot measure directly the extent or balance of their predispositions for delivering each model.

Conclusions

While small work teams pose obstacles to simple random assignment of treatment providers to deliver experimental practices, the random assignment of victims and offenders to two different models of service might be made more externally valid by use of partial random assignment of service providers.

中文翻译：

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小型工作组中的外部效度和实验与对照治疗提供者的分配：研究笔记

目标

当罪犯或受害人被随机分配接受实验性治疗与当前治疗时，结果的外部有效性可能取决于类似治疗提供者是否提供了不同治疗。当治疗提供者自愿在实验中提供创新的实践时，不清楚结果是否取决于治疗的内容，提供者对新实践的热情，还是两者都取决于。在这种情况下，我们描述为新疗法的志愿者易感性的潜力提出了外部有效性的问题。

方法

我们描述了与长期的调解方法相比，丹麦七个警察区的29个调解员中有14个调解员提供了一种新的恢复性会议方法，在罪犯与其受害者之间进行面对面的会议。

结果

我们与所有七名地区调解负责人及其所有29位调解人进行了谈判，以使用14位调解员的部分随机分配来提供新的恢复性模型。14名经过培训的新方法提供者在几个可衡量的特征上与继续使用现有模型的其他15个调解人基本相似，但是我们无法直接衡量其提供每种模型的倾向性的程度或平衡。

结论

虽然小型工作团队阻碍了提供服务的简单随机分配服务提供者进行实验实践，但通过使用服务提供者的部分随机分配，可以使受害者和犯罪者对两种不同服务模式的随机分配在外部更有效。