Editorial In many countries, the systems of early childhood education and care (ECEC) are facing major reforms, such as an expansion of the daycare infrastructure to cover younger ages or the stronger emphasis on early education and learning. In line with increased expectations, the question of quality and impact arises. A core question for the governance of ECEC systems as well as for the legitimization of public investments in these systems refers to the impact of ECEC on child development and educational success. Answering this question with the help of empirical evidence turns out to be a difficult endeavor. A whole bunch of both methodological challenges as well as pragmatic barriers for empirical research emerge. Reducing inequalities or even compensating for disadvantages in the area of (early) education are important political aims for children. Empirical studies therefore try to figure out if and under what conditions ECEC participation can reduce the social gradient in educational attainment. Empirical data can provide different kinds of knowledge that are valuable for governing ECEC systems (see Fig. 1). Descriptive knowledge informs about the prevailing reality, for instance about the ECEC participation rate of defined age groups (e.g., under 3-year-olds) in a specified jurisdiction (e.g., state) at a specific reference date. In order to derive such descriptive knowledge from available data, specific methodological criteria have to be met (e.g., representativeness). Explicative knowledge informs about the causal linkages assumed between the observable pedagogical quality in ECEC settings (‘process quality’) and structural factors (‘structural quality’) or child outcomes. Operative knowledge informs about those conditions that can be controlled by ECEC policy measures and that have an impact on the structural quality of ECEC settings. This kind of knowledge is meant when we talk about evidence-informed policy interventions. Different types of studies on ECEC deliver different kinds of knowledge, as will be explained in the following. Here we list and discuss those data sources or study types that are established and used in many countries to inform ECEC policy.

中文翻译：

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ECEC中的纵向研究：将研究转化为政策行动的挑战

社论在许多国家，幼儿教育和照料系统（ECEC）面临着重大改革，例如扩大日托基础设施以覆盖年轻人，或者更加重视早期教育和学习。与期望的提高相一致，出现了质量和影响的问题。ECEC系统的治理以及这些系统中公共投资的合法性的核心问题是ECEC对儿童发展和教育成功的影响。依靠经验证据来回答这个问题是一项艰巨的努力。大量的方法论挑战以及实证研究的实际障碍出现了。减少（早期）教育领域的不平等甚至弥补不利条件是儿童的重要政治目标。因此，实证研究试图弄清ECEC参与是否以及在什么条件下可以降低受教育程度的社会梯度。经验数据可以提供不同种类的知识，这些知识对于治理ECEC系统具有重要意义（见图1）。描述性知识告知了当前的现实，例如有关特定参考日期（特定州）（例如州）内特定年龄段（例如3岁以下）的ECEC参与率。为了从可用数据中获得这种描述性知识，必须满足特定的方法标准（例如，代表性）。详尽的知识说明了ECEC设置中可观察的教学质量（“过程质量”）与结构因素（“结构质量”）或儿童结局之间的因果联系。操作知识告知可以由ECEC政策措施控制的条件，这些条件会影响ECEC设置的结构质量。当我们谈论有据可依的政策干预措施时，就意味着这种知识。关于ECEC的不同类型的研究提供了不同种类的知识，下面将对此进行说明。在此，我们列出并讨论在许多国家建立并用于指导ECEC政策的数据源或研究类型。操作知识告知可以由ECEC政策措施控制的条件，这些条件会影响ECEC设置的结构质量。当我们谈论有据可依的政策干预措施时，就意味着这种知识。关于ECEC的不同类型的研究提供了不同种类的知识，下面将对此进行说明。在此，我们列出并讨论在许多国家建立并用于指导ECEC政策的数据源或研究类型。操作知识告知可以由ECEC政策措施控制的条件，这些条件会影响ECEC设置的结构质量。当我们谈论有据可依的政策干预措施时，就意味着这种知识。关于ECEC的不同类型的研究提供了不同种类的知识，下面将对此进行说明。在此，我们列出并讨论在许多国家建立并用于指导ECEC政策的数据源或研究类型。