  When training and evaluating machine reading comprehension models, it is very
important to work with high-quality datasets that are also representative of
real-world reading comprehension tasks. This requirement includes, for
instance, having questions that are based on texts of different genres and
require generating inferences or reflecting on the reading material.
  In this article we turn our attention to RACE, a dataset of English texts and
corresponding multiple-choice questions (MCQs). Each MCQ consists of a question
and four alternatives (of which one is the correct answer). RACE was
constructed by Chinese teachers of English for human reading comprehension and
is widely used as training material for machine reading comprehension models.
By construction, RACE should satisfy the aforementioned quality requirements
and the purpose of this article is to check whether they are indeed satisfied.
  We provide a detailed analysis of the test set of RACE for high-school
students (1045 texts and 3498 corresponding MCQs) including (1) an evaluation
of the difficulty of each MCQ and (2) annotations for the relevant pieces of
the texts (called "bases") that are used to justify the plausibility of each
alternative. A considerable number of MCQs appear not to fulfill basic
requirements for this type of reading comprehension tasks, so we additionally
identify the high-quality subset of the evaluated RACE corpus. We also
demonstrate that the distribution of the positions of the bases for the
alternatives is biased towards certain parts of texts, which is not necessarily
desirable when evaluating MCQ answering and generation models.
