A common question from research students, when the first self-indulgent spell of reading begins to weary them, is “When will I know I have read enough?” My answer usually is, “You’ll know!” This might not seem very helpful, but it is certainly accurate. The students start off with a few key articles, then extend their reading list by following up interesting-looking references cited in these early papers, and then systematically search for relevant new articles using Google Scholar, online library search-engines, and journals with promising titles. Eventually, the circle begins to close, and most of the helpful articles being discovered are those that have already been mentioned (and read) in earlier articles. Within the broad area of the chosen research topic, the student will have identified a high percentage of the most relevant journal articles and books that will be needed to give a comprehensive description of the highs and lows of this research topic. But the question will still be asked, “Is this enough?”
There are several answers to this. At its simplest, it is never enough. There will always be the possibility of missing important articles, either because they have been published in less well-known journals, or because they are older than a cut-off date (this is more important for fast-moving research areas), or simply because the keywords, meta-tagging, or article titles simply fail to attract the researchers attention. So, if we accept that it is difficult to list 100% of the relevant literature on a particular research topic, the supervisor can encourage the research student to do two important things. Firstly, to establish a clearer focus for their research by using their now-extensive knowledge of the relevant literature on their topic to define a tighter area of interest for further study. By now it will be obvious that the research could branch out in any number of new directions, but also obvious that this “scatter-gun” approach is less likely to be effective, in time and effort, in obtaining any meaningful answers. To solve many complex problems it is normally necessary to identify a number of problematic research questions, and then investigate them one-at-a-time.
Secondly, and this is crucial, the supervisor now needs to encourage the research student to articulate their chosen research methodology, identify the best methods of gathering new data, and then make a start in gathering that data. The student can read and read and read, but at some stage they also need to jump into the unknown. There are only two common characteristics of all PhD research, regardless of the discipline or the research methods; the finished presentation (usually the dissertation) needs to be demonstrably the work of the student (students in a team need to clearly identify their own contribution), and it needs to make a contribution (however small) of original work to expand upon our understanding of the research subject. In reality, the student will continue to read and add relevant new citations right up to the moment of submission (and possibly afterwards, if the examiners require it!). However, there are also other critical tasks to attend to. The initial reading should provide a good baseline of understanding for the student to quickly move on to other stages in the research process, including writing down the literature review, deciding on data collection methods, obtaining ethical clearance, and getting down to the exciting stage of breaking new research territory.