Peninsula Technology Assessment Group, College of Medicine and Health, University of Exeter, Exeter, UK.
Department of Public Health, Environments and Society, London School of Hygiene and Tropical Medicine, London, UK.
Soc Sci Med. 2021 Jun;279:113984. doi: 10.1016/j.socscimed.2021.113984. Epub 2021 May 3.
Realist evaluations aim to evaluate interventions by understanding the mechanisms they trigger, assessing not merely what works but what works for whom, under what conditions, and how. Significant disagreement in the literature exists as to whether randomized trials can be used as a tool for realist evaluation. INCLUSIVE, which was the first realist randomized trial explicitly designed as such, evaluated the impact of Learning Together, a school-based intervention for students aged 12-15 that included restorative practice, on bullying victimisation, mental wellbeing and psychological problems. Drawing on hypotheses generated through qualitative research, this analysis tested if school belonging was a mediator of intervention effects, and in which contexts. We estimated a series of fully longitudinal multilevel moderated mediation models including intervention allocation, student reports of school belonging at 24 months and victimisation and wellbeing outcomes at 36 months, and stratified on the basis of whether, at baseline, schools were: a) rated 'outstanding' for leadership, b) below the median for average levels of victimisation, and c) above the median on school inclusivity. Findings suggested that in unstratified models, belonging was not a mediator for any outcome; but in each of the strata defined above, belonging was a significant mediator at the student level. However, in the strata where belonging was not a mediator, the intervention still had a significant effect on each outcome. Analyses point to a strong but conditional role for belonging as a mediator of intervention pathways; in schools where belonging was not a mediator (e.g. above-median victimisation levels), other mechanisms may have been activated. This is consistent with a realist understanding of context-mechanism linkages generating outcomes. Our analyses suggest that realist evaluations can be pursued within randomized trials and that such analyses can offer more nuanced evidence regarding in which contexts interventions might effectively be implemented.
真实主义评价旨在通过了解干预措施引发的机制来评估干预措施，不仅评估其效果，还要评估其在何种条件下对谁有效以及如何有效。关于随机试验是否可作为真实主义评价的工具，文献中存在很大分歧。INCLUSIVE 是首个明确为此设计的真实主义随机试验，评估了针对 12-15 岁学生的基于学校的干预措施 Learning Together 的效果，该干预措施包括修复实践，以减少欺凌受害、改善心理健康和解决心理问题。该分析利用定性研究中产生的假设，检验了学校归属感是否是干预效果的中介因素，以及在哪些情况下是中介因素。我们估计了一系列完全纵向多层次调节中介模型，包括干预分配、学生在 24 个月时的学校归属感报告以及 36 个月时的受害和幸福感结果，并根据基线时学校是否存在以下情况进行分层：a）领导力被评为“杰出”，b）受害率低于平均值，c）学校包容性高于平均值。研究结果表明，在非分层模型中，归属感不是任何结果的中介因素；但在上述定义的每个分层中，归属感在学生层面上是一个显著的中介因素。然而，在归属感不是中介因素的分层中，干预措施对每个结果仍然有显著影响。分析表明，归属感作为干预途径的中介因素具有强大但有条件的作用；在归属感不是中介因素的学校（例如，受害率高于平均值），可能已经激活了其他机制。这与对背景-机制联系产生结果的真实主义理解是一致的。我们的分析表明，真实主义评价可以在随机试验中进行，并且此类分析可以提供更细致的证据，说明干预措施在哪些情况下可能有效实施。
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