For almost a century, the U.S. military has been a pioneer in the field of using aptitude tests to evaluate an individual’s potential for service. The organization also uses the test to determine aptitude for various military occupational specialties (MOS). The use of aptitude tests began during World War I. While the group-administered Army Alpha test measured verbal and numerical ability as well as general knowledge, the Army Beta test was used to evaluate illiterate, unschooled and non-English speaking volunteers and draftees. The Army and Navy General Classifications Tests replaced the Alpha and Beta tests as a means to measure cognitive ability during World War II. The results of these tests, as well as additional classification exams, were used to assign recruits to a particular MOS.
Once you have learned about yourself, you are ready to begin exploring different career options. Chances for a rewarding career are improved if you select a career field that matches your interests, values, skills, and abilities. While learning about various careers, you should be constantly asking yourself, “How well does this career match my current interests, values, and abilities?” and “Will this career lead to a lifestyle I want?”
AFQT scores are the primary measure of recruit potential. Figure 2.7 indicates the percentage of NPS recruits who scored at or above the 50th percentile (Categories I–IIIA) since FY 1973. Numerical data are in Appendix D, Table D-12. The drop in Category I–IIIA recruits after FY 1976 was due primarily to the miscalibration of the ASVAB.  In FY 1976, when new versions of the ASVAB were introduced, an error in calibrating the score scales made the new versions "easier" than the old versions (i.e., applicants received test scores higher than their actual ability). In FY 1980, an independent study of the calibration was made and the test was correctly calibrated. Then, Congress added legal provisions stipulating that no more than 20 percent of accessions could be in Category IV and that such accessions had to be high school diploma graduates.  However, as previously stated, Defense Planning Guidance decreases this limit even further, allowing no more than 4 percent of recruits to come from Category IV.
In the 2000s, women can serve on U.S. combat ships, including in command roles. They are permitted to serve on submarines. Women can fly military aircraft and make up 2% of all pilots in the U.S. Military. In 2003, Major Kim Campbell was awarded the Distinguished Flying Cross for landing her combat damaged A-10 Thunderbolt II with no hydraulic control and only one functional engine after being struck by hostile fire over Baghdad.