Fig. 4

Category characteristic curve of item 4 showing the probability of highest response. y-axis: probability of response option; x-axis: estimated Theta values; Because of ordered responses the curves are arranged from category zero (K = 0, left side) to category 4 (K = 4, right side). To ease interpretation vertical lines at the crossing points of the response categories were added. A respondent with a Theta lower than − 0.17 is likely to respond category 0, a respondent with a Theta between − 0.17 to 0.7 is likely to respond category 1 and so on