Table 4 represents item difficulty, item fit statistics and category frequency for each item of the PedsQLTM 4.0 for self- and proxy-reports.
The difficulty estimates that join on the 'no change' line, represented as the solid black line on the Figure, represent items that keep the same level of difficulty with time.
Much of the controversy revolves around general interpretations of holistic results from raw, un-trialled tests that accumulate data from deletions representing items of widely differing difficulty.
Three studied items were included in the first testlet, representing items with low (b k = −1), medium (b k = 0), and high (b k = 1) difficulty parameters.
Figure 2 shows clearly how well the increasing item difficulty represents the modeled hierarchy in the difficulty levels.
Significant diagnostic main effects represented group differences in item difficulty hierarchy.
DeMars (2010) explained that in IRT, the item difficulty (b) represents the proficiency of the test takers, half of which are expected to answer the item correctly.
For clinical application, using logits scores could precisely represent the disability level, and using the item difficulty could help clinicians design progressive programs for patients with back pain.
The results show how changes of ICT-specific task characteristics influenced item difficulty without changing the represented construct.
Can the item difficulty be controlled by the investigated factors?
