Before setting the research question for the project you are planning, we recommend that you conduct a review of the relevant existing scientific literature.
This will allow you to exclude the possibility that the research question has already been answered, and will provide an up to date overview of the current knowledge and research in the field.
The information gathered during the review can then be used to inform the design of your project, ensuring that it has a clearly defined aim that will fill an identified gap in the current knowledge and add value to the field.
The approach you take to the review will depend on the topic and type of study you are planning. For example a clinical trial may require a thorough systematic review, while for a qualitative observational study a lighter review of existing literature, or description of how this new project fits in with prior work may be more appropriate.
In England, you may be able to obtain advice on protocol design, including literature review, from the NIHR Research Design Services.