Personnel may be recruited or conscripted, depending on the system chosen by the state. Most military personnel are males; the minority proportion of female personnel varyies internationally (approximately 3% in India,[8] 10% in the UK,[9] 13% in Sweden,[10] 16% in the US,[11] and 27% in South Africa[12]). While two-thirds of states now recruit or conscript only adults, as of 2017 50 states still relied partly on children under the age of 18 (usually aged 16 or 17) to staff their armed forces.[13]
Each of the five services employs a single Senior Enlisted Advisor at departmental level. This individual is the highest ranking enlisted member within that respective service and functions as the chief advisor to the service secretary, service chief and Congress on matters concerning the enlisted force. These individuals carry responsibilities and protocol requirements equivalent to three-star general or flag officers. They are as follows:

The human capital shortage may be worse than the shortage in ships. A report by the Maritime Administration to Congress highlighted the problem. The report “estimates that 11,768 qualified mariners ... are available to crew the Ready Reserve Force ... the estimated demand for mariners [in an emergency] is 13,607.” Given the shortage, those mariners who are available “may have to endure prolonged assignments or tours of duty until the emergency is over,” which will decrease effectiveness, increase errors and — of greatest concern — delay deploying the forces necessary to win a large-scale conflict.

Sergeant Leigh Ann Hester became the first woman to receive the Silver Star, the third-highest U.S. decoration for valor, for direct participation in combat. In Afghanistan, Monica Lin Brown was presented the Silver Star for shielding wounded soldiers with her body.[43] In March 2012, the U.S. military had two women, Ann E. Dunwoody and Janet C. Wolfenbarger, with the rank of four-star general.[44][45] In 2016, Air Force General Lori Robinson became the first female officer to command a major Unified Combatant Command (USNORTHCOM) in the history of the United States Armed Forces.[46]
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).