Classical Test Theory (CTT) has many defects,namely the estimations of its parameters depend on the subjects,the estimation of ability level depends on the items,and it offers only average precision of estimation.

• 经典测验理论 (CTT)的主要缺点有 :对测题难度、区分度及测验信度的估计依赖于被试组 ；对被试能力的估计依赖于所使用的测验题目 ；只提供平均测量精度等 .