8. Use the following passage to answer questions 8 and 9. Harry went to the drugstore and purchased band-aids, pain relievers and cold medication. He also picked up two prescriptions. He then stopped by the hardware store and bought nails, screws and a first aid kit. Finally, he went to the grocery store and bought orange juice, flour and eggs. Where did Harry buy the first aid kit?
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).