As of 2017, the U.S. spends about US$610 billion annually to fund its military forces and Overseas Contingency Operations. Put together, the U.S. constitutes roughly 40 percent of the world's military expenditures. The U.S. Armed Forces has significant capabilities in both defense and power projection due to its large budget, resulting in advanced and powerful technologies which enables a widespread deployment of the force around the world, including around 800 military bases outside the United States. The U.S. Air Force is the world's largest air force, the U.S. Navy is the world's largest navy by tonnage, and the U.S. Navy and the U.S. Marine Corps combined are the world's second largest air arm. In terms of size, the U.S. Coast Guard is the world's 12th largest naval force. 
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).
The four most important sections of the test—Word Knowledge, Paragraph Comprehension, Arithmetic Reasoning, and Mathematics Knowledge-make up your Armed Forces Qualifications Test (AFQT) score. Your AFQT score ranges from 0 to 100 and determines if you are able to enlist in the military and which jobs and programs you may qualify for when you are in.
The AFQT has been used in non-military settings as a proxy measure of intelligence, for example, in Herrnstein & Murray's book The Bell Curve. Because of the test's significance both inside and outside military settings, it is important to examine what the test measures, i.e. to evaluate the construct validity of the AFQT. Kaufman's 2010 review stated that David Marks (2010) scanned the literature for datasets containing test estimates for populations or groups taking both the AFQT and tests of literacy. One study on nine groups of soldiers differing in job and reading ability found a correlation of .96 between the AFQT and reading achievement (Sticht, Caylor, Kern, & Fox, 1972). Another study showed significant improvements among Black and Hispanic populations in their AFQT scores between 1980 and 1992 while Whites only showed a slight decrement (Kilburn, Hanser, & Klerman, 1998). Another study obtained reading scores for 17-year olds for those same ethnic groups and dates (Campbell et al., 2000) and found a correlation of .997 between reading scores and AFQT scores. This nearly perfect correlation was based on six pairs of data points from six independent population samples evaluated by two separate groups of investigators. According to Marks, "On the basis of the studies summarized here, there can be little doubt that the Armed Forces Qualifications Test is a measure of literacy." However, it is important to note that AFQT has been shown to correlate more highly with classic IQ tests than they do with one another, and that the "crystallized" intelligence measured by AFQT is measured very similarly by Wechsler, in particular.
Both you and your counselor will receive a copy of the results. Before you take the ASVAB, you will be asked to sign a statement authorizing the Department of Defense to score your test and return your results to your school. Each school determines if it will release your scores to the military services. If you are a junior, a senior, or a postsecondary school student, a recruiter may contact you. This can occur whether or not you take the ASVAB.
As of 31 December 2010, U.S. Armed Forces troops were stationed in 150 countries; the number of non-contingent deployments per country ranges from 1 in Suriname to over 50,000 in Germany. Some of the largest deployments are: 103,700 in Afghanistan, 52,440 in Germany (see list), 35,688 in Japan (USFJ), 28,500 in South Korea (USFK), 9,660 in Italy and 9,015 in the United Kingdom. These numbers change frequently due to the regular recall and deployment of units.
The military uses the verbal expression (VE) score to measure your communicative ability. The score goes toward computing the AFQT score as well as many of the military’s line scores. The military brass determine your VE score by first adding the value of your Word Knowledge (WK) raw score to your Paragraph Comprehension (PC) raw score. The result is then converted to a scaled score ranging from 20 to 62.
Air Force recruits must score at least 36 points the 99-point ASVAB. The overall ASVAB score is known as the AFQT score, or Armed Forces Qualification Test score. Exceptions may be made, however, for a handful of high school graduates who can score as low as 31. The vast majority, some 70 percent, of those accepted for an Air Force enlistment achieve a score of 50 or above.
Obviously, the most important way to prepare to take the test is to spend plenty of time reviewing practice test questions. Look at questions from all sections of the test, but pay special attention to questions on the Word Knowledge, Paragraph Comprehension, Arithmetic Reasoning, and Mathematics Knowledge sections, which will be used to calculate your Armed Forces Qualification Test (AFQT) score for enlistment.
The AFQT score is the most important ASVAB score, because it determines if you can enlist in the U.S. Army. However, the U.S. Army also converts the ASVAB test scores into 10 other composite score areas known as "line scores" that determine what MOS an individual may qualify for. Listed below are the parts of the ASVAB that affect your AFQT test scores and each of the ten line scores.
It's important to understand the difference between the ASVAB Standard Scores, and the ASVAB AFQT score. Test takers will receive a separate score for each of the nine sections on the ASVAB. These scores are known as Standard Scores. A Standard Score is used to determine how the test taker compares to the "average" 18-23 year old American on that part of the ASVAB. Not long ago, a large number of people in this age group were given the tests, and these results are the benchmark for Standard Scores. Around half the people in this age group will score a 50 or higher, and about 16% will score a 60 or higher. In other words, the scoring is based on a standard bell curve distribution. Standard Scores are very important when it comes to determining which military job a person will be assigned to.
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.