You can assess your current knowledge and identify gaps. As a result you are able to:
Scope: The ability to assess current knowledge and identify gaps.
You need to be able to determine
The exact parameters of your search.
Whether or not the question should be separated into different specific areas for ready identification of sources within those areas.
How comprehensive it needs to be? How detailed do you need to be? Will it be a review of ALL relevant material or will the scope be limited to more recent material? How can you justify this?
How extensive should it be? You may have too much material to cover so you will need to put some limits in place on the project.
How broad can your scope be? Should it draw on literature from in related disciplines? You may not be able to conduct some research due to constraints imposed by time, cost or availability of materials.
Which sources are relevant for your purposes? You may wish to consider various sources from the information landscape for your discipline. This may help you systematically consider all sources of information on which you can draw.
You can consider the scope by examining the type of information as above or the type of research ie by methodological approaches, theoretical issues, qualitative or quantitative research.
Will you examine only English language material or will you also include research in other languages?
The more reading you do the better informed you and your research will be and the more accurately you will be able to refine the scope of your research. Background reading will enable you to identify gaps in the literature by:
And hence help you define the scope of your own search.