* This item was also used in the 1992 National Adult Literacy Survey (NALS).

This item has a difficulty level of 340, meaning that people must possess a skill level of 340 to have an 80% probability of performing this task. Note, though, that people with a skill level of 300 have a 56% probability of performing the task, and those with a skill level of 250 have a 24% probability of being able to perform the task. This illustrates that even though people may not be at the level of skill demanded for having an 80% probability of performing the task, they may nonetheless be able to perform it, albeit with a lower probability of success.

The YALS technical report states that, "Successful performance was determined to be that point on the item characteristic curve (ICC) at which an individual has an 80% probability of correct response to a given task or 80% of the people respond to the task correctly. Therefore, population estimates at specified points along each scale represent an 80% probability criterion. Use of this criterion does not imply that individuals scoring below a given level will be unable to respond correctly to any task above his/her estimated level of proficiency" (see Figure 68, p.99 for sources of this quote: Kirsch & Jungeblut, 1986, p. IV-12).