ASVAB Standard Scores
Standard Scores are scores that have a fixed mean and standard deviation in the population of examinees. A Standard Score indicates how many units of the standard deviation a particular score is above or below the mean. In the case of the ASVAB subtests, the mean is set to 50 and the standard deviation is set to 10. Thus, a Standard Score of 40 indicates that the examinee scored 1 standard deviation below the mean. A Standard Score of 70 indicates that the examinee scored 2 standard deviations above the mean.
Scores on the individual ASVAB subtests are reported as Standard Scores. Standard Scores are scores that have a meaning relative to a national sample of youth aged 18 to 23. About half the population scores at or above a Standard Score of 50 and about 16% of the population scores at or above a Standard Score of 60.
ASVAB AFQT Scores
Examinees also receive a score on what is called the Armed Forces Qualification Test (AFQT). AFQT scores are computed using the Standard Scores from four ASVAB subtests: Arithmetic Reasoning (AR), Mathematics Knowledge (MK), Paragraph Comprehension (PC), and Word Knowledge (WK). 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 norming study conducted in 1997. Thus, an AFQT score of 90 indicates that the examinee scored as well as or better than 90% of the nationally-representative sample of 18 to 23 year old youth. An AFQT score of 50 indicates that the examinee scored as well as or better than 50% of the nationally-representative sample.
AFQT scores are divided into categories, as shown in the list below.
- AFQT Category I: 93-99
- AFQT Category II: 65-92
- AFQT Category IIIA: 50-64
- AFQT Category IIIB: 31-49
- AFQT Category IVA: 21-30
- AFQT Category IVB: 16-20
- AFQT Category IVC: 10-15
- AFQT Category V: 1-9
ASVAB Score Requirements
The various branches adjust the required scores from time to time and may do so without notice. Also, recruitment requires a higher score for someone with a GED than for someone with a high school diploma. ASVAB scores are used primarily to determine enlistment eligibility, assign applicants to military jobs, and aid students in career exploration.
Each branch of the US armed forces has minimum ASVAB scores required to enter specific fields. For example, to qualify in the area of aerospace ground equipment for the US Air Force, scores in two areas must be extremely high. The mechanical comprehension area requires a score of of M47 and Electrical skills of E28. If you score lower in these areas, you will be placed in another area of expertise in which you prove to have more knowledge and aptitude.
Each branch of the military has specific acronyms or words used to refer to the various types of work necessary to maintain a ready armed service. You can look up the scores necessary for any area you wish to enter online or speak to your local recruiter for that military branch.
ASVAB Score Equating
ASVAB scores are statistically leveled and balanced across different forms and administration modes through a process called “equating”. The reason scores are equated is to level the playing field so that all ASVAB scores can be compared against one another regardless of which exam form or administration mode is provided to each and every test taker.
Scores from both CAT-ASVAB and P&P-ASVAB are computed using formulas that take into account the difficulty of the questions and the correctness of the answers. As the result of a procedure called “equating,” CAT-ASVAB scores have exactly the same meaning as P&P-ASVAB scores. CAT-ASVAB subtests are not harder or easier than the P&P-ASVAB subtests because the scores are equivalent. Equating test scores is not new. It is the same procedure used in making the different P&P-ASVAB forms equivalent to each other.
ASVAB Item Response Theory
The ASVAB scoring system is based on an Item Response Theory (IRT) model. Item Response Theory is a theory that enables test questions and examinee abilities to be placed on the same scale, thereby allowing tests to be tailored to the specific ability level of each examinee and scores to be expressed on the same scale regardless of the combination of items that are taken.
The Item Response Theory model underlying ASVAB scoring is the three-parameter logistic (3PL) model. The three-parameter logistic 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 three-parameter logistic 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).
For both the paper-and-pencil (P&P) and computerized adaptive testing (CAT) versions of the ASVAB, the three-parameter logistic model is used to compute final ability estimates for examinees. For the CAT-ASVAB the three-parameter logistic model is also used to select items. When a CAT-ASVAB session is started, every examinee is assigned an initial ability estimate of = 0.0, which is the mean of the expected distribution of examinee abilities. After each new item is administered, the scored response is used to update the ability estimate. A sequential Bayesian procedure is used for this purpose. When the test is completed (or the time limit exceeded), a final ability estimate is computed as the mode of the posterior distribution (Bayesian modal estimate).