率差标准的确定和难度常模的建立——对2004—2009年高考北京卷的实证研究

The Standards for Difficulty Difference and the Construction of Difficulty Norms

难度常模即具有特定局部区分功能的一组组题目的按难度值排列的有序集合，其核心是难度系数与区分功能的对应关系。题目区分功能的定位是难度常模制作过程的关键一步，本研究为此划分了目标群体和临界参照群体，并结合统计和数学方法为各种区分类型设定了率差数量标准。基于上述方法，结合大量数据统计与分析，高考北京卷各个学科的难度常模得以初步建立，但其发展和完善仍留待数据的进一步积累和研究的进一步深入。

The difficulty norms are the essence of which is the corresponding ordinal sets of item clusters with specific discriminative function, the relationship between difficulty indexes and discriminative function. The recognition of the discriminative function of items is the key process of the construction of difficulty norms. To achieve this goal, target group and reference group have been put forward and the standards for difficulty difference have been set through statistics and analysis. Furthermore, the difficulty norms of each subject of the College Entrance Examination in Beijing have been sketched out based on the study and analysis mentioned above, while the improvement of such norms still depend on the accumulation of data and the extension of research.