Although research on the primary and secondary effects of social origin aims at understanding the relative importance of performance and choice in educational decision making processes, it tends to downplay that primary effects are a function of two separate components: (a) the level of social inequality in academic performance and (b) the effect of academic performance on educational decisions. Examining trends in educational inequalities in Denmark from 2002 through 2016, I demonstrate that separately considering these two components leads to new interpretations of why social class inequalities in educational decisions change over time. I find that although both primary and secondary effects of social origin are declining in Denmark over the period, the decline in primary effects occurs in spite of increasing social class gaps in academic performance. In contrast, the decline results from decreasing educational returns to academic performance. My findings suggest that conventional comparisons of primary and secondary effects of social origin across contexts such as countries or time periods may mask the pathways through which social class differentials in educational decisions arise.

尽管对社会起源的主要和次要影响的研究旨在了解绩效和选择在教育决策过程中的相对重要性，但它往往低估了主要影响是两个独立成分的函数：（a）社会不平等程度（b）学术表现对教育决定的影响。考察了2002年至2016年丹麦教育不平等的趋势，我证明了单独考虑这两个因素可以对教育决策中的社会阶级不平等随时间变化的原因做出新的解释。我发现，尽管在此期间，丹麦的社会起源的主要影响和次要影响都在下降，尽管社会阶层的学习成绩差距越来越大，但主要影响仍在下降。相反，这种下降是由于教育对学术成绩的回报减少所致。我的发现表明，在国家或时期等背景下，对社会起源的主要和次要作用的常规比较可能掩盖了教育决策中社会阶层差异产生的途径。