Each year, many high school and postsecondary students take the free Armed Services Vocational Aptitude battery (ASVAB). The ASVAB is the most widely used multiple-aptitude test battery in the world. It consists of eight tests that measure your skills and abilities in the following areas: General Science; Arithmetic Reasoning; World Knowledge; Paragraph Comprehension; Mathematics Knowledge; Electronics Information; Auto and Shop Information; Mechanical Comprehension.
The underlying model used for the ASVAB is a three-parameter logistic (3PL) model. This model represents the probability that an examinee at a given level of ability will respond correctly to an individual item with given characteristics. The characteristics used are difficulty, discrimination and guessing (this refers to the likelihood that a very low ability examinee would respond correctly simply by guessing).
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.