Item response models

Item response models may refer either to item-response theory (IRT) or Rasch models. Although not synonymous, both forms of model are measurement or psychometric methods that can be applied to a wide range of data, including data derived from patient-reported outcome measures (PROMs). A particular strength of these models is that their focus is on the item-level rather than test-level (as seen in traditional or classical test theory). This has several benefits, the two most important of which are:

1. Researchers can identify (and potentially remove or amend) poorly performing items, such as those that are not relevant to the target audience.
2. Item banks (drawn from many PROMs) together with computer-adaptive testing may enable the creation of shorter, more relevant, but equally accurate tests.