The Armed Services Vocational Aptitude Battery is more commonly known as the ASVAB Test. If you are interested in a military career, you will need to pass this challenging test in order to qualify. It is used for all branches of the military which includes the Army, Navy, Air Force, Marines, National Guard, and Coast Guard. It is also used to gauge your abilities in specific areas that may be relevant to your job assignments within the military. For more information about the exact details of this exam, check out our article titled What is the ASVAB Test?
One set of ASVAB scores – Career Exploration Scores – tells you your current strengths in verbal, math, science, and technical skills.  The scores allow you to compare your test performance with that of other students at your grade level and can help you determine your readiness for further education and training in different career areas.  You will also receive a Military Entrance Score that is important for entry into the Armed Services.  You can discuss your score with a military recruiter.
The IRT model underlying ASVAB scoring is the three-parameter logistic (3PL) model. The 3PL model represents the probability that an examinee at a given level of ability will respond correctly to an individual item with given characteristics. Specifically, the item characteristics represented in the 3PL model are difficulty, discrimination (i.e., how well the item discriminates among examinees of differing levels of ability), and guessing (i.e., the likelihood that a very low ability examinee would respond correctly simply by guessing).

One ASVAB sub-measure, the Armed Forces Qualification Test (AFQT)--which is just a separate analysis of the same tests that focuses only on four of the subtests--is also population-referenced, but its score from 1-99 is a percentile score. This means that if you score a 73, you scored as well as or higher than 73% of test-takers in the national sample.