This study examined the mediation and moderation of membership in a demographic group underrepresented in physics classes on course outcomes measured by course grades and Force and Motion Conceptual Evaluation (FMCE) post-test scores. The study used a large dataset ($N=4490$) of course grades, SAT and ACT mathematics scores (ACTM), and matched FMCE pretest and post-test scores to investigate differences by gender, underrepresented ethnic or racial minority (UERM) status, and status as a first-generation college student (FGCS). For UERM and FGCS students, ACTM and pretest scores significantly mediated the relation of membership in the demographic group and both course grade and post-test score. Differences between minority and majority members of these groups were largely removed by controlling for ACTM and pretest scores. The overwhelming majority of the effect acted through ACTM for course grade (60% and 45%, respectively), while more of the effect acted through pretest score for the post-test (36% and 48%, respectively). As such, for these groups prior preparation measures predict physics outcomes (course grades or post-test scores) differently. The mediational relations for gender were dramatically different. No mediation was detected for the relation of gender to course grade because no significant difference in course grade existed. Sixty percent of the effect of gender on post-test score was not explained by either ACTM or pretest score; pretest score accounted for 38% of the effect. As such, the majority of the difference in post-test scores between men and women was not explained by either ACTM or pretest scores. Significant moderation was also detected showing that the relation of these variables was not consistent for members of all demographic groups.

中文翻译：

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先验准备对物理中代表性不足的学生表现差异的中介作用

这项研究检查了在物理课程中代表性不足的人口统计学群体中成员的中介作用和调节作用，该结果通过课程成绩和“力与运动概念评估”（FMCE）测试后分数来衡量。该研究使用了大型数据集（$ñ=4490$）课程成绩，SAT和ACT数学分数（ACTM），以及匹配的FMCE测验前和测验后分数，以调查按性别，代表性不足的族裔或种族少数群体（UERM）身份以及第一代大学生（FGCS）身份的差异）。对于UERM和FGCS学生，ACTM和测验前成绩显着调节了人口统计学组成员与课程成绩和测验后成绩之间的关系。通过控制ACTM和预测分数，可以很大程度上消除这些群体中少数群体和多数成员之间的差异。绝大多数的效果是通过ACTM在课程成绩上起作用的（分别为60％和45％），而更多的效果是通过测试前的分数来进行后测的（分别为36％和48％）。因此，对于这些组，事先的准备措施对物理结果（课程成绩或测试后分数）的预测不同。性别之间的调解关系截然不同。未发现性别与课程成绩之间的调解，因为课程成绩之间不存在显着差异。ACTM或测验前分数均未解释性别对测验后分数影响的60％；预测分数占效果的38％。因此，男女之间测验分数的大部分差异都无法通过ACTM或测验分数来解释。还检测到显着的适度性，表明这些变量的关系对于所有人口统计群体的成员而言并不一致。未发现性别与课程成绩之间的调解，因为课程成绩之间不存在显着差异。ACTM或测验前分数均未解释性别对测验后分数影响的60％；预测分数占效果的38％。因此，男女之间测验分数的大部分差异都无法通过ACTM或测验分数来解释。还检测到显着的适度性，表明这些变量的关系对于所有人口统计群体的成员而言并不一致。未发现性别与课程成绩之间的调解，因为课程成绩之间不存在显着差异。ACTM或测验前分数均未解释性别对测验后分数影响的60％；预测分数占效果的38％。因此，男女之间测验分数的大部分差异都无法通过ACTM或测验分数来解释。还检测到显着的适度性，表明这些变量的关系对于所有人口统计群体的成员而言并不一致。男女之间测验分数的大部分差异都无法通过ACTM或测验分数来解释。还检测到显着的适度性，表明这些变量的关系对于所有人口统计群体的成员而言并不一致。男女之间测验分数的大部分差异都无法通过ACTM或测验分数来解释。还检测到显着的适度性，表明这些变量的关系对于所有人口统计群体的成员而言并不一致。