There are two main purposes of the literature review of research, firstly to provide a background introduction to the chosen research area, and secondly to provide a justification for the research about to be undertaken by documenting how the topic under investigation relates to previous research. To do this, the researcher will need to cast a net widely and be open to a wide range of prior research which is directly, or indirectly, relevant to their specific research topic. This is where the first problem might arise. How does a new researcher know if something is relevant or simply something of tangential interest?
There is the “need to know” information and the “good to know” information, and both are required. The literature review can come in different styles, normally as the opening chapter to a dissertation, but the review could be spread throughout several chapters, especially in a multi-disciplinary study. It is a bit like a detective story – the text has to let the reader know what the key issues are, how the research area has developed, and what has been tried before? In setting out the highlights of the history of the specific research topic, the reader needs to know the details of what is already known about the research topic, and consequently, what aspects are less well-known and might be the subject of the subsequent research by the student. I like to think of this as the “landscape” of the proposed research – the high-points and the low-points, the obviously recognisable landmarks and perhaps some of the hidden depths. By the end of the literature review, the reader should have a good understanding of the main features of the topic, why it is important, and what the academically contested areas are.
Then there is the “good to know” information, and this can be more problematic. In the body of previous research, there will have been many false-starts and blind alleys. There will be respected academic literature which has investigated the topic, set out their results, and given an interpretation of the known facts, only to have been overtaken by subsequent research and shown to be wrong, or at best only partially informed. This is good information to know because it might save time by indicating a line of enquiry which has been tried and found to be fruitless, or a method of gathering data which has been improved upon and might therefore be worth looking at again. The longevity and the depth required for PhD research means that the student has opportunities to explore the realms of the possible, the unusual or off-chance lines of investigation which just might lead to a breakthrough, or a new way of thinking about the research problem. As long as this “off-piste” work is kept within reason, and not allowed to detrimentally influence the main flow of the research thinking, it is to be encouraged, because there are many great discoveries which have started when someone thought, “What if I do this instead…?” The evidential basis for many of these directional changes in thinking originates in the review of the known academic literature. That is why it is good to read widely, read deeply, and read often.