A military brat is a colloquial term for a child with at least one parent who served as an active duty member (vice reserve) in the armed forces. Children of armed forces members may move around to different military bases or international postings, which gives them a childhood differing from the norm. Unlike common usage of the term brat, when it is used in this context, it is not necessarily a derogatory term.
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).