The underlying model used for the ASVAB is a three-parameter logistic (3PL) model. This model represents the probability that an examinee at a given level of ability will respond correctly to an individual item with given characteristics. The characteristics used are difficulty, discrimination and guessing (this refers to the likelihood that a very low ability examinee would respond correctly simply by guessing).
If you didn't earn a score that was high enough to be accepted to your chosen branch of the military, or if you didn't earn a line score high enough to qualify for a desired career option, then you may retake the ASVAB. You must wait a full month before you can take the ASVAB a second time. If you wish to take the test a third time, you must wait another month from the date of your second attempt. After the third attempt, there is a waiting period of 6 months before you can take the test again.
The Armed Forces Qualification Test (AFQT) is used by all of the Services to determine if an applicant is eligible for the military. Four of the ASVAB subtests are combined to form the AFQT. It measures general cognitive ability and is composed of verbal and mathematics subtests. AFQT scores are grouped into categories for reporting purposes. The table below shows the AFQT categories and the percentile score ranges corresponding to the categories. Applicants that score in AFQT category IIIA or higher may qualify for enlistment incentives.