test item difficulty

Item Response Theory takes the hypothesis that every test item has its own features such as difficulty, discrimination and others, which are not related to the sample and neither to other items.

条目反应理论认为，每个测验条目有其自身固有的特征，比如难度、区分度等，这些特征与样本无关，也与其它条目无关。

The statistical model is put forward to test the accuracy of item difficulty indexes in the test papers given by the educational experts.

提出一个统计模型，用于检验试题库中由专家给出试题难度这一指标的准确性。

Third, test designers should attach great importance to the difficulty of each item when designing test papers.

第三，考试设计者应重视每条题目的难度。