This case study describes the use of a capacity measurement tool and a performance measurement tool to evaluate the effect of an assistive device, using upper limb prosthesis as an example of assistive device. The case describes the benefits of using the International Classification of Functioning, Disability and Health to understand “capacity” and “performance” and the importance of using correct measurement tools to measure these two concepts. A patient-reported questionnaire that collects data about daily performance in wide range of activities from real-life environment is a good option for measuring performance when assessment in real-life environment is not possible.
However, behind the measurements, there were several considerations in how I can minimize errors in the measurements. This was done by providing pictures to explain patient-reported questions and by providing training before data collection. It was also beneficial to have an extended recruiting period to achieve a representative sample. This case study provides an insight into the practical details of how a clinical evaluation project was carried out through the eyes of a clinical researcher.