A clinical investigation plan for a medical device must outline and justify all objectives of the clinical investigation, present and justify the investigational design and methodology, and state principal features of  the statistical analysis. A clinical investigation report should summarise the plan, explain any deviations from it, and present and discuss the results of the clinical investigation. Preparing clinical investigational documents requires collaboration with numerous professionals with expertise in clinical practice, statistics, data management, monitoring, and regulatory requirements. While separate guidelines apply for medical devices and pharmaceuticals, with differences in terminology and safety reporting among other factors, they offer similar guidance on good clinical practice, adapted for the product type. As a medical writer, you should not be afraid to ask questions when things are unclear, or to offer input.