The so-called "deviation value" refers to the deviation value of the relative average value, which is a calculation formula value of Japanese students' intelligence and academic ability. The deviation value reflects the ranking of each person among all the candidates. In Japan, deviation value is regarded as a correct reflection of learning level, and it naturally becomes a standard for evaluating learning ability.

Japan enrolls students in spring, and conducts a national unified examination for senior high school graduates every winter. When enrolling students, universities often use the deviation value of this exam to evaluate students' learning ability, which is an important (in fact, often the only) criterion for admission. Therefore, it leads to the dissatisfaction of candidates and the criticism of public opinion, and also leads to the tendency of focusing only on scores and not on conduct in high school education.

Application of the formula:

The deviation value can eliminate the influence of the difficulty of the test paper and marking, so you can compare the scores of the same person or different people on different test papers, as long as the scores are converted into deviation values.

If the exam is national, the deviation value obtained indicates the position of the candidate among the national candidates. Of course, the ranking can also be directly used for comparison, but because the number of candidates in different years is different, the specific ranking may not be of great reference value. Therefore, candidates can apply for schools according to their own deviation values, and schools can also enroll students according to the deviation values of candidates.

Japan formally adopted the deviation system in the examination, namely 1964. In the 1970s, some private high schools in Tokyo generally began to select candidates with deviation values. In this way, schools that organize teaching for the purpose of entrance examination actually conduct daily teaching and entrance guidance centered on the deviation value. The deviation value of junior high school students often becomes an important factor in determining their future whereabouts and entering high school.