Throughout the product development cycle, it is important to conduct usability research. In the US this process is mandated and detailed by the FDA. Early in the process, you need to confirm confidence in your design via User Preference testing. Later on, you may conduct formative testing to ensure your design properly mitigates risk or to discover new risks. Finally, we conduct summative testing to ensure the device is safe for its intended users in their intended environment.
For an FDA submission or US-based device, this process is straightforward. However, what if you are designing a device that will seek initial clearance in the US, then will transition to international markets? Language barriers, long-distance logistics, and various unknowns can result in disastrous outcomes. Best practices are presented for lab-based testing in addition to contextual inquiry field research.