A student who got band 2 in Korean in the March achievement test gets band 4 in the September mock assessment. The amount of study went up and the band went down. At this point many students tear up their whole approach to studying. But in a good number of cases, what changed was not ability but the people sitting the test.

Not all "mock exams" have the same organiser or the same candidates

The tests a final-year student sits over the course of a year fall into two categories.

The national joint achievement test is run by metropolitan and provincial offices of education. The tests in March and April fall here, and only enrolled students sit them. Graduates are not eligible.

The CSAT mock assessment is run by the Korea Institute for Curriculum and Evaluation. It takes place in June and September, and enrolled students and graduates sit it together. It is different in character in that the body that sets the CSAT runs it with a cohort close to the actual CSAT cohort.

The structural reason bands fall

A band is a relative position. Get the same score with a different group of people and the band moves.

In March there are only enrolled students. By June, graduates who have already been preparing for a year or more join. In September there are slightly more graduates again, and in the CSAT the number of graduates rises relative to June or September while enrolled students fall.

One more thing compounds this: lower-scoring candidates drop out in stages while stronger ones keep joining. Students who have already secured a place through early admission either do not sit the CSAT or do not push themselves on it, while graduates focused on regular admission stay to the end. As a result a band can slip regardless of the student's own ability. A student going from band 1 in March to band 2 in September is a natural consequence of this structure.

So which results should you plan around?

The practical conclusion is simple.

• March and April achievement tests: use them only to check the state of your learning. Judging which universities are within reach from these results will almost certainly overestimate.
• The June mock assessment: the first test graduates join. Suitable as the first baseline for building an early admission strategy.
• The September mock assessment: closest to the actual CSAT cohort. It falls just before early admission applications, so it is the basis for final decisions.

In particular, using March results to judge whether you will meet a minimum CSAT requirement is risky. It has to be recalculated on June and September results.

The indicator to look at before the band

There is a more useful indicator during the stretch when bands are unstable.

It is the trend in raw score and standard score. Bands move with the cohort, but the raw score shows how much the student actually got right. If the band went down but the raw score went up, ability improved and only the relative position slipped. If the raw score fell too, that is grounds for reviewing how the student is studying.

The other is the type of question missed. Within the same band 4, questions left undone for lack of time and questions got wrong despite knowing the material need completely different remedies. Sorting the answer sheet by type is far more productive than reacting to a single band. The structure of regular admission applications is taken up in University Admissions.

In summary

There is no reason to relax because March went well, and none to fall apart because September slipped. Knowing just one fact — March is enrolled students only, and from June graduates are in too — changes how you read a result sheet. Put the baseline at June and September, and in between look at raw scores and error types rather than bands.