[News Terms] The Standard Score as the Criterion for Judging 'Mulsuneung' and 'Bulsuneung'

The reason the 2024 College Scholastic Ability Test (CSAT) held on the 16th of last month is being evaluated as a 'Bulsuneung' (extremely difficult exam) lies in the record-high maximum standard scores (perfect scores) in Korean and Mathematics.

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The standard score indicates how far a test taker's raw score deviates from the average and was introduced in 2005 when test takers were allowed to choose their exam subjects. Since each test taker selects different subjects and the difficulty varies among chosen subjects, it was difficult to evaluate using only raw scores, which led to the adoption of this scoring system.

The method of calculating the standard score is somewhat complex. First, the test taker's raw score is subtracted by the average score of the chosen subject, then divided by the standard deviation of the group to which the test taker belongs. The resulting value is multiplied by the standard deviation of the subject, and then the average score is added back to obtain the standard score. Essentially, it can be understood as subtracting the average score from the test taker's raw score. Typically, if the exam is difficult and the average score is low, the standard score will be high. Conversely, if the exam is easy and the average score is high, the standard score will be low.

Since the number of test takers and averages differ by subject, the maximum standard scores for perfect scorers also vary by subject. The difference in standard scores among perfect scorers is due to the choice of subjects. In some cases, test takers who took subjects with higher maximum standard scores may have a higher standard score than perfect scorers in other subjects.

Meanwhile, according to the 2024 CSAT scoring results announced by the Korea Institute for Curriculum and Evaluation on the 7th, the highest standard score in Korean was 150 points, which is 16 points higher than last year's CSAT (134 points). Since the introduction of the standard score system in 2005, the Korean highest score reaching 150 points is the second time after the 2019 CSAT. The highest standard score in Mathematics also rose by 3 points from last year (145 points) to 148 points. This is the highest since the 2020 CSAT, when the level-based exams for Type Ga and Na were still in place (Na type 149 points). Generally, if the highest standard score in Korean or Mathematics exceeds 140 points, the exam is considered difficult, and if it exceeds 150 points, it is regarded as a Bulsuneung (extremely difficult exam).