A test developer's choice of which style or format to use when developing a written test is usually arbitrary given that there is no single invariant standard for testing. Be that as it may, certain test styles and format have become more widely used than others. Below is a list of those formats of test items that are widely used by educators and test developers to construct paper or computer-based tests. As a result, these tests may consist of only one type of test item format (., multiple choice test, essay test) or may have a combination of different test item formats (., a test that has multiple choice and essay items).
The corresponding percentile of each scaled score varies from test to test—for example, in 2003, a scaled score of 800 in both sections of the SAT Reasoning Test corresponded to a percentile of , while a scaled score of 800 in the SAT Physics Test corresponded to the 94th percentile. The differences in what scores mean with regard to percentiles are due to the content of the exam and the caliber of students choosing to take each exam. Subject Tests are subject to intensive study (often in the form of an AP , which is relatively more difficult), and only those who know they will perform well tend to take these tests, creating a skewed distribution of scores.