The scavenging effect (percentage) was calculated as per the formulae in (Duan et al. 2006).
Missing items: percentage of patients with any missing items; Missing score: percentage of patients with any missing score; Floor effect: percentage of patients with worst possible score (0); Ceiling effect: percentage of patients with best possible score (100).
To determine the content validity, we calculated the ceiling effect (percentage) for each separate study and we pooled data to measure the weighted mean.
The likelihood ratio (LR), the additive effect, percentage of variance explained (R) and the 2 LOD confidence interval are also presented.
5 Danish and German translation validation studies of the OHS reported varied ceiling percentages, 19.9% for the Danish and no ceiling effect (percentage not given) in the German version.
However this relative low floor effect (percentage of subjects with the lowest score) would be an appealing issue of the OIDP for using in longitudinal studies with dental patients since a global improvement of score is desirable to be detected.
Moreover, ceiling effect was studied (percentage of patients with maximum score, indicating a better clinical situation), together with floor effect (percentage of patients with minimum score, indicating a worse clinical outcome), for every item and for global scoring of every instrument used.
Missing data and floor and ceiling effects (percentages of participants indicating minimum and maximum scores) of the CASP-19 were investigated in order to verify the validity and reliability of scale content (Ware & Gandek, 1998).
For dummy variables, the incremental effects percentage changed in ADM IN ^ COST = 100 exp β ^ k - 1.
