Strengths and limitations of the study
The central strength of this process evaluation is that a heterogeneous subsample with maximum variation regarding the variable expression was formed. This purposeful sampling strategy ensures representativeness and diversity of the family carers and therefore increases the significance of the data. On the other hand, we did not know a priori if the selected and categorized variables would really achieve the sampling of information-rich informants that cover the range of variation and if, therefore, an iterative approach of sampling and re-sampling to draw an appropriate sample, e.g., according to the grounded theory [