Higher levels of item discrimination reflect a higher degree of information that the item provides about the respondent’s ability level. As a result, the value of ai is an indicator of how much information the item provides about the respondent’s ability. Because the 2PL model considers how much information is provided by each item (via ai), in estimating ability using the 2PL model different items are assigned different weights according to the item’s value of ai; the higher the value of ai, the more weight is assigned to the item in estimating ability.