This journal has pioneered and championed thinking about complexity in evaluation for more than two decades. We have devoted less attention to how evaluation theory and methods translate into the practical world of government and policy making. Committing an entire special issue to the outputs of CECAN, a research centre working on the complexity/practice interface, may go some way to re-balancing our coverage of this important topic. The introductory essay authored by guest editors, references key theoretical and methodological articles, many published in Evaluation from the late 1990s onwards. I would encourage readers when they have read the content of this issue, to revisit some of these articles. As I see it we may not have yet achieved a ‘unity of theory and practice’, but we are taking steps, however tentatively, in that direction.

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编者注

该杂志在二十多年的时间里一直率先倡导评估的复杂性。我们很少关注评估理论和方法如何转化为政府和政策制定的现实世界。将整个特殊问题提交给CECAN（一个研究复杂性/实践界面的研究中心）的输出，可能会以某种方式重新平衡我们对这一重要主题的覆盖。客座编辑撰写的介绍性论文，引用了重要的理论和方法论文章，其中许多发表在《评估》上从1990年代后期开始。当读者阅读本期的内容时，我会鼓励他们重新阅读其中一些文章。正如我所看到的，我们可能尚未实现“理论与实践的统一”，但是我们正在朝着这个方向（尽管尝试性地）采取步骤。