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).

There are essentially two options when it comes to preparing for this test. First, a person can attempt to reassess all of the information that they learned over a decade by spending hours compiling information. Secondly, a person can find a specially formatted ASVAB practice test that covers all areas of both the written test and computerized test. Clearly, the best choice is the ASVAB practice test. The question becomes “Where does one find an accurate ASVAB practice test?”
AFQT scores are reported as percentiles between 1-99. An AFQT percentile score indicates the percentage of examinees in a reference group that scored at or below that particular score. For current AFQT scores, the reference group is a sample of 18 to 23 year old youth who took the ASVAB as part of a national study conducted in 1997. Thus, an AFQT score of 95 indicates that the examinee scored as well as or better than 95% of the nationally-representative sample of 18 to 23 year olds. An AFQT score of 60 indicates that the examinee scored as well as or better than 60% of the nationally-representative sample.

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.