Quantitative structure—PKDD
Response distributions for the PKDD data were skewed towards the right, i.e., respondents tended to report scores at the lower ends of the response options (low severity). This was observed particularly for Items 3 and 4 (Fig. PKDD item response distributions at baseline. Inter-item Spearman correlation matrices for PKDD (The GRM demonstrated excellent model fit (CBased on this model, a weighted scoring algorithm was developed for the PKDD and implemented using the EAP sum score conversion tables. The scoring algorithm was as follows. Within each day, scores within respective domains were summed using the collapsed response categories. These sum scores were then converted to T-score transformed EAP sum scores using a “look-up” table, and then these daily scores were averaged over a seven-day period if at least 4 days of data were available in a week (otherwise the score was treated as missing) (Additional file 