Because most of the concepts and methods used by the military, and many of its systems are not found in commercial branches, much of the material is researched, designed, developed, and offered for inclusion in arsenals by military science organisations within the overall structure of the military. Military scientists are therefore found to interact with all Arms and Services of the armed forces, and at all levels of the military hierarchy of command.

Note: While the U.S. Navy is older than the Marine Corps,[52] the Marine Corps takes precedence due to previous inconsistencies in the Navy's birth date. The Marine Corps has recognized its observed birth date on a more consistent basis. The Second Continental Congress is considered to have established the Navy on 13 October 1775 by authorizing the purchase of ships, but did not actually pass the "Rules for the Regulation of the Navy of the United Colonies" until 27 November 1775.[53] The Marine Corps was established by act of said Congress on 10 November 1775. The Navy did not officially recognize 13 October 1775 as its birth date until 1972, when then–Chief of Naval Operations Admiral Elmo Zumwalt authorized it to be observed as such.[52]
All test takers are given a summary results sheet that shows their percentile score in every test area. A percentile score of 50 means that a score was achieved that was better than 50 percent of all test takers. Percentile scores are given specifically for test takers of their gender and their grade level. Information obtained from the test is only shared with agencies within the Department of Defense. Test takers are informed that their specific scores will be used for up to two years for recruiting purposes. After two years, test scores will be used for research purposes only.
There have been attempts to produce a military strength index: this is an example taken from a Credit Suisse report in September 2015.[32] The factors under consideration for that military strength indicator and their total weights were: number of active personnel in the army (5%), tanks (10%), attack helicopters (15%), aircraft (20%), aircraft carriers (25%), and submarines (25%). It was practically impossible to make an estimation of the actual training of the armed forces. [33] These were the results:
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.