Fig. 2

Wright map: the subject-ability and item-difficulty map of the Arabic CSD module. The line represents the measure of the construct satisfaction with device in linear logit units with average difficulty of items set to 0 (indicated by M). On the left column is the distribution of individual’s “ability/agreement” along the construct (satisfaction): each "#" denotes three individuals while "." denotes one to two individuals. Top to bottom measures indicate lower to higher satisfaction with device. On the right column is the item difficulty measure for each category along the construct based on the rating scale model. The higher the item estimate, the more difficult the item was for the cohort to endorse/agree with (i.e., showing lower scores and indicating less satisfaction with this item). The highest and lowest item response category step calibrations are indicated with arrows