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.
The United States Coast Guard traces its origin to the founding of the Revenue Cutter Service on 4 August 1790 which merged with the United States Life-Saving Service on 28 January 1915 to establish the Coast Guard. The United States Air Force was established as an independent service on 18 September 1947; it traces its origin to the formation of the Aeronautical Division, U.S. Signal Corps, which was formed 1 August 1907 and was part of the Army Air Forces before becoming an independent service as per the National Security Act of 1947.
Mathematics Knowledge tests the ability to solve problems by applying knowledge of mathematical concepts and applications. The problems focus on concepts and algorithms, and involve number theory, numeration, algebraic operations and equations, geometry, measurement and probability. Mathematics Knowledge is one factor that characterizes mathematics comprehension; it also assesses logical thinking.