Measurement strategy The outcome measures for this study are given in the measurement section of the registration document. The original measurement strategy was to use full measures that have already been applied in this field. Piloting of the original plan indicated that this would not be feasible as there were too many items, many of which would not be appropriate or relevant to the context. Instead, the measurement strategy was to use outcome indicators: single items; indices by cumulating responses over several related items; or full measures/subscales with total scores validated using Rasch analysis.