Statistical methods for repeated qualitative assessments on scales

Assessments of auditory communication are commonly performed with questionnaires or multi-item instruments. The item responses generate ordered categorical data. The aim of the work reported here was to present a statistical approach that takes account of the non-metric properties of data from rating scales for description of multi-item assessments and for evaluation of change in a study concerning the function of and satisfaction with hearing aids. A small data set from an ongoing study at the Ahlsén Research Institute, Orebro University Hospital was used in the worked examples. The use of individual and median group profiles provided an interpretable description of the data. By means of the ranking approach, which ties the ranks to the pairs of data, the systematic group change in hearing function was evaluated separately from the additional individual changes. The use and misuse of parametric statistical methods on ordered categorical data are also discussed.