For more detailed questions, we recommend that you contact a statistics consultant at your institution or attend a seminar/online training for SPSS. Please understand that we cannot answer every question, especially if it is specific to your study.
Scales can only be evaluated if less than 30% of the items of a scale are missing. In this case, a mean substitution is performed.
Calculation of the scales transformed to 100
According to the KINDLR manual, scales transformed to values from 0-100 are calculated as follows:
((scale value - lowest possible value)/possible range of raw value)x100.
The scale value corresponds to the mean value of the respective scale over all items. In the syntax, however, the sum value is used. Both calculations are possible, since the lowest possible value and the possible range are each adjusted to the value used.
Additions to the transformation
Please note the following additions for the transformation of the scale values of the KINDLR into values from 0 to 100 (see Manual p.18, 2.5.3 and p.19, 2.5.3):
For all standardized versions of the KINDLR, the "lowest possible value" is 1. The "possible range" is 4 throughout, only for the children's version of the Kiddy-KINDL (interview) it is 2.
Analysis of disease-specific modules
In principle, the analysis can be conducted as stated in the manual with regard to the recoding of the items and the handling of missing values. With regard to the scales, good quality of life corresponds to a higher values.
Consistency of the self and parent report
Regarding the proxy problem, i.e. the comparison of data collected from children and adolescents with the data provided by their parents, we recommend the following publications from the field of "Quality of Life":