Each score on a GRE® Subject Test depends on the number of questions answered correctly in the time allotted. The number of questions answered correctly is converted to a scaled score through a process known as equating. The equating process accounts for minor variations in difficulty among the different test editions. Thus, a given scaled score reflects approximately the same level of ability regardless of the edition of the test that was taken.
Every Subject Test yields a total score. The Physics and Psychology Tests yield subscores in addition to the total score.
For these tests, the number of questions answered correctly that belong to each content area and the number of questions answered correctly on the whole test both contribute to each subscore. In most cases, questions that belong to a content area also require some ability in other content areas. By using the number of correct answers on the whole test in the computations of each subscore, the responses to the questions that belong to other content areas are allowed to contribute and the quality of the subscore is enhanced.
Subscores are also scaled through equating.