Fig. 1From: Development of a new Rasch-based scoring algorithm for the National Eye Institute Visual Functioning Questionnaire to improve its interpretabilityScale-To-Sample (Person–Item) Distribution for the NEI VFQÂ-25. The top panel shows the distribution of pooled participants on the visual functioning scale. The bottom panel maps the NEI VFQ-25 items (grouped by subscale) onto the same visual functioning scale, highlighting item difficulty. Vertical dashed lines indicate the lower (left) and upper (right) extent of instrument coverage for the pooled participant populationBack to article page