There are three key factors to consider when deciding which sources to include in your literature review draft, all of which come down to relevance and timeliness:
Your theoretical framework establishes your methodology and your approach to the research problem as being grounded in tried-and-tested methods and approaches. For this reason, older sources may be the most appropriate for this part of the literature review.
Look for foundational sources and authors—those whose methods and approaches are well-established and well-regarded in your field.
This involves answering the journalists’ questions: who, what, where, why, and how.
The problem you are addressing will have been explored and established by the work of other researchers (while your hypotheses/solutions are most likely original). You will therefore be using secondary research to answer these questions.
This will involve a mix of old and new sources, describing the “history” of the research context for your research question(s). It will provide a summary of the key research already conducted on your topic.
Establishing the research gap involves carefully assessing and curating the newest source and most recent research on your topic. The goal is not to summarize every single recent source relevant to your topic. Instead, you are looking for what these sources have left out or failed to achieve—these are the gaps into which your research will fall.
It needs to establish the research problem, provide a clear context in terms of existing research, and identify the need for further (your) research. Choose to include only and all sources that fulfill these objectives, and you will have a strong literature review.
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