There are two types of military history, although almost all texts have elements of both: descriptive history, that serves to chronicle conflicts without offering any statements about the causes, nature of conduct, the ending, and effects of a conflict; and analytical history, that seeks to offer statements about the causes, nature, ending, and aftermath of conflicts – as a means of deriving knowledge and understanding of conflicts as a whole, and prevent repetition of mistakes in future, to suggest better concepts or methods in employing forces, or to advocate the need for new technology.
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).