This study investigated the thematic and lexical characteristics of high-difficulty English reading items—commonly referred to as killer questions—in the Korean College Scholastic Ability Test (CSAT) between 2018 and 2025. Using text mining methods, including Latent Dirichlet Allocation (LDA) and CEFR-based lexical profiling, the analysis reveals that these items disproportionately addressed abstract, academic topics such as cultural heritage, moral dilemmas, and cognitive science. Lexical analysis further indicated that over 30% of the words used are at the C1 level or above, reflecting substantial vocabulary demands. These findings point to a misalignment with the national curriculum, which is designed to target B1–B2 proficiency with more familiar and accessible topics. The combined challenge of abstract themes and advanced vocabulary raises concerns about the construct validity and fairness of these items, suggesting that they may measure background knowledge or test-taking strategies rather than genuine English reading proficiency. The study concludes by calling for evidence-based item development and closer alignment with curricular goals to ensure valid and equitable high-stakes language assessment.

This study analyzed the patterns of relative clauses (RCs) used on the College Scholastic Ability Test (CSAT), a standardized test for college admissions in Korea. The researchers investigated the Noun Phrase Accessibility Hierarchy and the impact of the antecedent’s animacy on RCs. Also, it was explored how NPs in the subject position of object RCs affected language processing, specifically, the condition where relativizers were omitted and the reasons for producing passive subject RCs. Data were collected from the CSAT and mock tests from 2019 to 2023. The analysis of 622 RCs yielded the following results: First, the frequency of RCs appeared in the following order: subject RCs, object RCs, then OBL. Second, the object RCs showed a preference for inanimate antecedents whereas the subject RCs used did not show a preference for animate antecedents. Third, NPs in the subject position with sentences containing object RCs predominantly took the form of pronouns, with common nouns used less frequently.

This study examines the effects of text length and question type on Korean EFL readers’ reading comprehension of the fill-in-the-blank items in Korean CSAT. A total of 100 Korean EFL college students participated in the study. After divided into three different proficiency groups, the participants took a reading comprehension test which consisted of 4 reading passages (2 short and 2 long) from the Korean CSAT, followed by multiple-choice fill-in-the-blank questions and open-ended inference questions. The longer version of the passages was made from its originally restored version in which one or two paragraphs were added. The results showed that the college students performed better on the long passages than the short ones. In addition, the college students’ reading comprehension test performance was affected differently depending on the type of questions. The findings of the study provided implications on how to select and construct reading passages for high-stake nationwide examinations, such as the Korean CSAT.